Roll Observatory packages and add a roll script

analyzer/lib/src/generated/element.dart

-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// This code was auto-generated, is not intended to be edited, and is subject to
-// significant change. Please see the README file for more information.
-
-library engine.element;
-
-import 'dart:collection';
-
-import 'package:analyzer/src/generated/utilities_general.dart';
-import 'package:analyzer/src/task/dart.dart';
-import 'package:analyzer/task/model.dart'
-    show AnalysisTarget, ConstantEvaluationTarget;
-
-import 'ast.dart';
-import 'constant.dart' show EvaluationResultImpl;
-import 'engine.dart' show AnalysisContext, AnalysisEngine, AnalysisException;
-import 'html.dart' show XmlAttributeNode, XmlTagNode;
-import 'java_core.dart';
-import 'java_engine.dart';
-import 'resolver.dart';
-import 'scanner.dart' show Keyword;
-import 'sdk.dart' show DartSdk;
-import 'source.dart';
-import 'utilities_collection.dart';
-import 'utilities_dart.dart';
-
-/**
- * For AST nodes that could be in both the getter and setter contexts
- * ([IndexExpression]s and [SimpleIdentifier]s), the additional resolved
- * elements are stored in the AST node, in an [AuxiliaryElements]. Because
- * resolved elements are either statically resolved or resolved using propagated
- * type information, this class is a wrapper for a pair of [ExecutableElement]s,
- * not just a single [ExecutableElement].
- */
-class AuxiliaryElements {
-  /**
-   * The element based on propagated type information, or `null` if the AST
-   * structure has not been resolved or if the node could not be resolved.
-   */
-  final ExecutableElement propagatedElement;
-
-  /**
-   * The element based on static type information, or `null` if the AST
-   * structure has not been resolved or if the node could not be resolved.
-   */
-  final ExecutableElement staticElement;
-
-  /**
-   * Initialize a newly created pair to have both the [staticElement] and the
-   * [propagatedElement].
-   */
-  AuxiliaryElements(this.staticElement, this.propagatedElement);
-}
-
-/**
- * A [Type] that represents the type 'bottom'.
- */
-class BottomTypeImpl extends TypeImpl {
-  /**
-   * The unique instance of this class.
-   */
-  static BottomTypeImpl _INSTANCE = new BottomTypeImpl._();
-
-  /**
-   * Return the unique instance of this class.
-   */
-  static BottomTypeImpl get instance => _INSTANCE;
-
-  /**
-   * Prevent the creation of instances of this class.
-   */
-  BottomTypeImpl._() : super(null, "<bottom>");
-
-  @override
-  int get hashCode => 0;
-
-  @override
-  bool get isBottom => true;
-
-  @override
-  bool operator ==(Object object) => identical(object, this);
-
-  @override
-  bool isMoreSpecificThan(DartType type,
-      [bool withDynamic = false, Set<Element> visitedElements]) => true;
-
-  @override
-  bool isSubtypeOf(DartType type) => true;
-
-  @override
-  bool isSupertypeOf(DartType type) => false;
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) => this;
-
-  @override
-  BottomTypeImpl substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) => this;
-}
-
-/**
- * Type created internally if a circular reference is ever detected.  Behaves
- * like `dynamic`, except that when converted to a string it is displayed as
- * `...`.
- */
-class CircularTypeImpl extends DynamicTypeImpl {
-  CircularTypeImpl() : super._circular();
-
-  @override
-  int get hashCode => 1;
-
-  @override
-  bool operator ==(Object object) => object is CircularTypeImpl;
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write('...');
-  }
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) => this;
-}
-
-/**
- * An element that represents a class.
- */
-abstract class ClassElement implements TypeDefiningElement {
-  /**
-   * An empty list of class elements.
-   */
-  static const List<ClassElement> EMPTY_LIST = const <ClassElement>[];
-
-  /**
-   * Return a list containing all of the accessors (getters and setters)
-   * declared in this class.
-   */
-  List<PropertyAccessorElement> get accessors;
-
-  /**
-   * Return a list containing all the supertypes defined for this class and its
-   * supertypes. This includes superclasses, mixins and interfaces.
-   */
-  List<InterfaceType> get allSupertypes;
-
-  /**
-   * Return a list containing all of the constructors declared in this class.
-   */
-  List<ConstructorElement> get constructors;
-
-  /**
-   * Return a list containing all of the fields declared in this class.
-   */
-  List<FieldElement> get fields;
-
-  /**
-   * Return `true` if this class or its superclass declares a non-final instance
-   * field.
-   */
-  bool get hasNonFinalField;
-
-  /**
-   * Return `true` if this class has reference to super (so, for example, cannot
-   * be used as a mixin).
-   */
-  bool get hasReferenceToSuper;
-
-  /**
-   * Return `true` if this class declares a static member.
-   */
-  bool get hasStaticMember;
-
-  /**
-   * Return a list containing all of the interfaces that are implemented by this
-   * class.
-   *
-   * <b>Note:</b> Because the element model represents the state of the code, it
-   * is possible for it to be semantically invalid. In particular, it is not
-   * safe to assume that the inheritance structure of a class does not contain a
-   * cycle. Clients that traverse the inheritance structure must explicitly
-   * guard against infinite loops.
-   */
-  List<InterfaceType> get interfaces;
-
-  /**
-   * Return `true` if this class is abstract. A class is abstract if it has an
-   * explicit `abstract` modifier. Note, that this definition of <i>abstract</i>
-   * is different from <i>has unimplemented members</i>.
-   */
-  bool get isAbstract;
-
-  /**
-   * Return `true` if this class is defined by an enum declaration.
-   */
-  bool get isEnum;
-
-  /**
-   * Return `true` if this class is a mixin application.  A class is a mixin
-   * application if it was declared using the syntax "class A = B with C;".
-   */
-  bool get isMixinApplication;
-
-  /**
-   * Return `true` if this class [isProxy], or if it inherits the proxy
-   * annotation from a supertype.
-   */
-  bool get isOrInheritsProxy;
-
-  /**
-   * Return `true` if this element has an annotation of the form '@proxy'.
-   */
-  bool get isProxy;
-
-  /**
-   * Return `true` if this class is a mixin application.  Deprecated--please
-   * use [isMixinApplication] instead.
-   */
-  @deprecated
-  bool get isTypedef;
-
-  /**
-   * Return `true` if this class can validly be used as a mixin when defining
-   * another class. The behavior of this method is defined by the Dart Language
-   * Specification in section 9:
-   * <blockquote>
-   * It is a compile-time error if a declared or derived mixin refers to super.
-   * It is a compile-time error if a declared or derived mixin explicitly
-   * declares a constructor. It is a compile-time error if a mixin is derived
-   * from a class whose superclass is not Object.
-   * </blockquote>
-   */
-  bool get isValidMixin;
-
-  /**
-   * Return a list containing all of the methods declared in this class.
-   */
-  List<MethodElement> get methods;
-
-  /**
-   * Return a list containing all of the mixins that are applied to the class
-   * being extended in order to derive the superclass of this class.
-   *
-   * <b>Note:</b> Because the element model represents the state of the code, it
-   * is possible for it to be semantically invalid. In particular, it is not
-   * safe to assume that the inheritance structure of a class does not contain a
-   * cycle. Clients that traverse the inheritance structure must explicitly
-   * guard against infinite loops.
-   */
-  List<InterfaceType> get mixins;
-
-  /**
-   * Return the superclass of this class, or `null` if the class represents the
-   * class 'Object'. All other classes will have a non-`null` superclass. If the
-   * superclass was not explicitly declared then the implicit superclass
-   * 'Object' will be returned.
-   *
-   * <b>Note:</b> Because the element model represents the state of the code, it
-   * is possible for it to be semantically invalid. In particular, it is not
-   * safe to assume that the inheritance structure of a class does not contain a
-   * cycle. Clients that traverse the inheritance structure must explicitly
-   * guard against infinite loops.
-   */
-  InterfaceType get supertype;
-
-  @override
-  InterfaceType get type;
-
-  /**
-   * Return a list containing all of the type parameters declared for this
-   * class.
-   */
-  List<TypeParameterElement> get typeParameters;
-
-  /**
-   * Return the unnamed constructor declared in this class, or `null` if this
-   * class does not declare an unnamed constructor but does declare named
-   * constructors. The returned constructor will be synthetic if this class does
-   * not declare any constructors, in which case it will represent the default
-   * constructor for the class.
-   */
-  ConstructorElement get unnamedConstructor;
-
-  /**
-   * Return the resolved [ClassDeclaration] or [EnumDeclaration] node that
-   * declares this [ClassElement].
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  NamedCompilationUnitMember computeNode();
-
-  /**
-   * Return the field (synthetic or explicit) defined in this class that has the
-   * given [name], or `null` if this class does not define a field with the
-   * given name.
-   */
-  FieldElement getField(String name);
-
-  /**
-   * Return the element representing the getter with the given [name] that is
-   * declared in this class, or `null` if this class does not declare a getter
-   * with the given name.
-   */
-  PropertyAccessorElement getGetter(String name);
-
-  /**
-   * Return the element representing the method with the given [name] that is
-   * declared in this class, or `null` if this class does not declare a method
-   * with the given name.
-   */
-  MethodElement getMethod(String name);
-
-  /**
-   * Return the named constructor declared in this class with the given [name],
-   * or `null` if this class does not declare a named constructor with the given
-   * name.
-   */
-  ConstructorElement getNamedConstructor(String name);
-
-  /**
-   * Return the element representing the setter with the given [name] that is
-   * declared in this class, or `null` if this class does not declare a setter
-   * with the given name.
-   */
-  PropertyAccessorElement getSetter(String name);
-
-  /**
-   * Determine whether the given [constructor], which exists in the superclass
-   * of this class, is accessible to constructors in this class.
-   */
-  bool isSuperConstructorAccessible(ConstructorElement constructor);
-
-  /**
-   * Return the element representing the method that results from looking up the
-   * given [methodName] in this class with respect to the given [library],
-   * ignoring abstract methods, or `null` if the look up fails. The behavior of
-   * this method is defined by the Dart Language Specification in section
-   * 16.15.1:
-   * <blockquote>
-   * The result of looking up method <i>m</i> in class <i>C</i> with respect to
-   * library <i>L</i> is: If <i>C</i> declares an instance method named <i>m</i>
-   * that is accessible to <i>L</i>, then that method is the result of the
-   * lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the result
-   * of the lookup is the result of looking up method <i>m</i> in <i>S</i> with
-   * respect to <i>L</i>. Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  MethodElement lookUpConcreteMethod(String methodName, LibraryElement library);
-
-  /**
-   * Return the element representing the getter that results from looking up the
-   * given [getterName] in this class with respect to the given [library], or
-   * `null` if the look up fails. The behavior of this method is defined by the
-   * Dart Language Specification in section 16.15.2:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is: If <i>C</i> declares an
-   * instance getter (respectively setter) named <i>m</i> that is accessible to
-   * <i>L</i>, then that getter (respectively setter) is the result of the
-   * lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the result
-   * of the lookup is the result of looking up getter (respectively setter)
-   * <i>m</i> in <i>S</i> with respect to <i>L</i>. Otherwise, we say that the
-   * lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpGetter(
-      String getterName, LibraryElement library);
-
-  /**
-   * Return the element representing the getter that results from looking up the
-   * given [getterName] in the superclass of this class with respect to the
-   * given [library], ignoring abstract getters, or `null` if the look up fails.
-   * The behavior of this method is defined by the Dart Language Specification
-   * in section 16.15.2:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is: If <i>C</i> declares an
-   * instance getter (respectively setter) named <i>m</i> that is accessible to
-   * <i>L</i>, then that getter (respectively setter) is the result of the
-   * lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the result
-   * of the lookup is the result of looking up getter (respectively setter)
-   * <i>m</i> in <i>S</i> with respect to <i>L</i>. Otherwise, we say that the
-   * lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpInheritedConcreteGetter(
-      String getterName, LibraryElement library);
-
-  /**
-   * Return the element representing the method that results from looking up the
-   * given [methodName] in the superclass of this class with respect to the
-   * given [library], ignoring abstract methods, or `null` if the look up fails.
-   * The behavior of this method is defined by the Dart Language Specification
-   * in section 16.15.1:
-   * <blockquote>
-   * The result of looking up method <i>m</i> in class <i>C</i> with respect to
-   * library <i>L</i> is:  If <i>C</i> declares an instance method named
-   * <i>m</i> that is accessible to <i>L</i>, then that method is the result of
-   * the lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the
-   * result of the lookup is the result of looking up method <i>m</i> in
-   * <i>S</i> with respect to <i>L</i>. Otherwise, we say that the lookup has
-   * failed.
-   * </blockquote>
-   */
-  MethodElement lookUpInheritedConcreteMethod(
-      String methodName, LibraryElement library);
-
-  /**
-   * Return the element representing the setter that results from looking up the
-   * given [setterName] in the superclass of this class with respect to the
-   * given [library], ignoring abstract setters, or `null` if the look up fails.
-   * The behavior of this method is defined by the Dart Language Specification
-   * in section 16.15.2:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is:  If <i>C</i> declares an
-   * instance getter (respectively setter) named <i>m</i> that is accessible to
-   * <i>L</i>, then that getter (respectively setter) is the result of the
-   * lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the result
-   * of the lookup is the result of looking up getter (respectively setter)
-   * <i>m</i> in <i>S</i> with respect to <i>L</i>. Otherwise, we say that the
-   * lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpInheritedConcreteSetter(
-      String setterName, LibraryElement library);
-
-  /**
-   * Return the element representing the method that results from looking up the
-   * given [methodName] in the superclass of this class with respect to the
-   * given [library], or `null` if the look up fails. The behavior of this
-   * method is defined by the Dart Language Specification in section 16.15.1:
-   * <blockquote>
-   * The result of looking up method <i>m</i> in class <i>C</i> with respect to
-   * library <i>L</i> is:  If <i>C</i> declares an instance method named
-   * <i>m</i> that is accessible to <i>L</i>, then that method is the result of
-   * the lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the
-   * result of the lookup is the result of looking up method <i>m</i> in
-   * <i>S</i> with respect to <i>L</i>. Otherwise, we say that the lookup has
-   * failed.
-   * </blockquote>
-   */
-  MethodElement lookUpInheritedMethod(
-      String methodName, LibraryElement library);
-
-  /**
-   * Return the element representing the method that results from looking up the
-   * given [methodName] in this class with respect to the given [library], or
-   * `null` if the look up fails. The behavior of this method is defined by the
-   * Dart Language Specification in section 16.15.1:
-   * <blockquote>
-   * The result of looking up method <i>m</i> in class <i>C</i> with respect to
-   * library <i>L</i> is:  If <i>C</i> declares an instance method named
-   * <i>m</i> that is accessible to <i>L</i>, then that method is the result of
-   * the lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the
-   * result of the lookup is the result of looking up method <i>m</i> in
-   * <i>S</i> with respect to <i>L</i>. Otherwise, we say that the lookup has
-   * failed.
-   * </blockquote>
-   */
-  MethodElement lookUpMethod(String methodName, LibraryElement library);
-
-  /**
-   * Return the element representing the setter that results from looking up the
-   * given [setterName] in this class with respect to the given [library], or
-   * `null` if the look up fails. The behavior of this method is defined by the
-   * Dart Language Specification in section 16.15.2:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is: If <i>C</i> declares an
-   * instance getter (respectively setter) named <i>m</i> that is accessible to
-   * <i>L</i>, then that getter (respectively setter) is the result of the
-   * lookup. Otherwise, if <i>C</i> has a superclass <i>S</i>, then the result
-   * of the lookup is the result of looking up getter (respectively setter)
-   * <i>m</i> in <i>S</i> with respect to <i>L</i>. Otherwise, we say that the
-   * lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpSetter(
-      String setterName, LibraryElement library);
-}
-
-/**
- * A concrete implementation of a [ClassElement].
- */
-class ClassElementImpl extends ElementImpl implements ClassElement {
-  /**
-   * An empty list of class elements.
-   */
-  @deprecated // Use ClassElement.EMPTY_LIST
-  static const List<ClassElement> EMPTY_ARRAY = const <ClassElement>[];
-
-  /**
-   * A list containing all of the accessors (getters and setters) contained in
-   * this class.
-   */
-  List<PropertyAccessorElement> _accessors = PropertyAccessorElement.EMPTY_LIST;
-
-  /**
-   * For classes which are not mixin applications, a list containing all of the
-   * constructors contained in this class, or `null` if the list of
-   * constructors has not yet been built.
-   *
-   * For classes which are mixin applications, the list of constructors is
-   * computed on the fly by the [constructors] getter, and this field is
-   * `null`.
-   */
-  List<ConstructorElement> _constructors;
-
-  /**
-   * A list containing all of the fields contained in this class.
-   */
-  List<FieldElement> _fields = FieldElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the mixins that are applied to the class being
-   * extended in order to derive the superclass of this class.
-   */
-  List<InterfaceType> mixins = InterfaceType.EMPTY_LIST;
-
-  /**
-   * A list containing all of the interfaces that are implemented by this class.
-   */
-  List<InterfaceType> interfaces = InterfaceType.EMPTY_LIST;
-
-  /**
-   * A list containing all of the methods contained in this class.
-   */
-  List<MethodElement> _methods = MethodElement.EMPTY_LIST;
-
-  /**
-   * The superclass of the class, or `null` if the class does not have an
-   * explicit superclass.
-   */
-  InterfaceType supertype;
-
-  /**
-   * The type defined by the class.
-   */
-  InterfaceType type;
-
-  /**
-   * A list containing all of the type parameters defined for this class.
-   */
-  List<TypeParameterElement> _typeParameters = TypeParameterElement.EMPTY_LIST;
-
-  /**
-   * The [SourceRange] of the `with` clause, `null` if there is no one.
-   */
-  SourceRange withClauseRange;
-
-  /**
-   * Initialize a newly created class element to have the given [name] at the
-   * given [offset] in the file that contains the declaration of this element.
-   */
-  ClassElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created class element to have the given [name].
-   */
-  ClassElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Set whether this class is abstract.
-   */
-  void set abstract(bool isAbstract) {
-    setModifier(Modifier.ABSTRACT, isAbstract);
-  }
-
-  @override
-  List<PropertyAccessorElement> get accessors => _accessors;
-
-  /**
-   * Set the accessors contained in this class to the given [accessors].
-   */
-  void set accessors(List<PropertyAccessorElement> accessors) {
-    for (PropertyAccessorElement accessor in accessors) {
-      (accessor as PropertyAccessorElementImpl).enclosingElement = this;
-    }
-    this._accessors = accessors;
-  }
-
-  @override
-  List<InterfaceType> get allSupertypes {
-    List<InterfaceType> list = new List<InterfaceType>();
-    _collectAllSupertypes(list);
-    return list;
-  }
-
-  @override
-  List<ConstructorElement> get constructors {
-    if (!isMixinApplication) {
-      assert(_constructors != null);
-      return _constructors == null
-          ? ConstructorElement.EMPTY_LIST
-          : _constructors;
-    }
-
-    return _computeMixinAppConstructors();
-  }
-
-  /**
-   * Set the constructors contained in this class to the given [constructors].
-   *
-   * Should only be used for class elements that are not mixin applications.
-   */
-  void set constructors(List<ConstructorElement> constructors) {
-    assert(!isMixinApplication);
-    for (ConstructorElement constructor in constructors) {
-      (constructor as ConstructorElementImpl).enclosingElement = this;
-    }
-    this._constructors = constructors;
-  }
-
-  /**
-   * Return `true` if [CompileTimeErrorCode.MIXIN_HAS_NO_CONSTRUCTORS] should
-   * be reported for this class.
-   */
-  bool get doesMixinLackConstructors {
-    if (!isMixinApplication && mixins.isEmpty) {
-      // This class is not a mixin application and it doesn't have a "with"
-      // clause, so CompileTimeErrorCode.MIXIN_HAS_NO_CONSTRUCTORS is
-      // inapplicable.
-      return false;
-    }
-    if (supertype == null) {
-      // Should never happen, since Object is the only class that has no
-      // supertype, and it should have been caught by the test above.
-      assert(false);
-      return false;
-    }
-    // Find the nearest class in the supertype chain that is not a mixin
-    // application.
-    ClassElement nearestNonMixinClass = supertype.element;
-    if (nearestNonMixinClass.isMixinApplication) {
-      // Use a list to keep track of the classes we've seen, so that we won't
-      // go into an infinite loop in the event of a non-trivial loop in the
-      // class hierarchy.
-      List<ClassElementImpl> classesSeen = <ClassElementImpl>[this];
-      while (nearestNonMixinClass.isMixinApplication) {
-        if (classesSeen.contains(nearestNonMixinClass)) {
-          // Loop in the class hierarchy (which is reported elsewhere).  Don't
-          // confuse the user with further errors.
-          return false;
-        }
-        classesSeen.add(nearestNonMixinClass);
-        if (nearestNonMixinClass.supertype == null) {
-          // Should never happen, since Object is the only class that has no
-          // supertype, and it is not a mixin application.
-          assert(false);
-          return false;
-        }
-        nearestNonMixinClass = nearestNonMixinClass.supertype.element;
-      }
-    }
-    return !nearestNonMixinClass.constructors.any(isSuperConstructorAccessible);
-  }
-
-  /**
-   * Set whether this class is defined by an enum declaration.
-   */
-  void set enum2(bool isEnum) {
-    setModifier(Modifier.ENUM, isEnum);
-  }
-
-  @override
-  List<FieldElement> get fields => _fields;
-
-  /**
-   * Set the fields contained in this class to the given [fields].
-   */
-  void set fields(List<FieldElement> fields) {
-    for (FieldElement field in fields) {
-      (field as FieldElementImpl).enclosingElement = this;
-    }
-    this._fields = fields;
-  }
-
-  @override
-  bool get hasNonFinalField {
-    List<ClassElement> classesToVisit = new List<ClassElement>();
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    classesToVisit.add(this);
-    while (!classesToVisit.isEmpty) {
-      ClassElement currentElement = classesToVisit.removeAt(0);
-      if (visitedClasses.add(currentElement)) {
-        // check fields
-        for (FieldElement field in currentElement.fields) {
-          if (!field.isFinal &&
-              !field.isConst &&
-              !field.isStatic &&
-              !field.isSynthetic) {
-            return true;
-          }
-        }
-        // check mixins
-        for (InterfaceType mixinType in currentElement.mixins) {
-          ClassElement mixinElement = mixinType.element;
-          classesToVisit.add(mixinElement);
-        }
-        // check super
-        InterfaceType supertype = currentElement.supertype;
-        if (supertype != null) {
-          ClassElement superElement = supertype.element;
-          if (superElement != null) {
-            classesToVisit.add(superElement);
-          }
-        }
-      }
-    }
-    // not found
-    return false;
-  }
-
-  @override
-  bool get hasReferenceToSuper => hasModifier(Modifier.REFERENCES_SUPER);
-
-  /**
-   * Set whether this class references 'super'.
-   */
-  void set hasReferenceToSuper(bool isReferencedSuper) {
-    setModifier(Modifier.REFERENCES_SUPER, isReferencedSuper);
-  }
-
-  @override
-  bool get hasStaticMember {
-    for (MethodElement method in _methods) {
-      if (method.isStatic) {
-        return true;
-      }
-    }
-    for (PropertyAccessorElement accessor in _accessors) {
-      if (accessor.isStatic) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  bool get isAbstract => hasModifier(Modifier.ABSTRACT);
-
-  @override
-  bool get isEnum => hasModifier(Modifier.ENUM);
-
-  @override
-  bool get isMixinApplication => hasModifier(Modifier.MIXIN_APPLICATION);
-
-  @override
-  bool get isOrInheritsProxy =>
-      _safeIsOrInheritsProxy(this, new HashSet<ClassElement>());
-
-  @override
-  bool get isProxy {
-    for (ElementAnnotation annotation in metadata) {
-      if (annotation.isProxy) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  @deprecated
-  bool get isTypedef => isMixinApplication;
-
-  @override
-  bool get isValidMixin => hasModifier(Modifier.MIXIN);
-
-  @override
-  ElementKind get kind => ElementKind.CLASS;
-
-  @override
-  List<MethodElement> get methods => _methods;
-
-  /**
-   * Set the methods contained in this class to the given [methods].
-   */
-  void set methods(List<MethodElement> methods) {
-    for (MethodElement method in methods) {
-      (method as MethodElementImpl).enclosingElement = this;
-    }
-    this._methods = methods;
-  }
-
-  /**
-   * Set whether this class is a mixin application.
-   */
-  void set mixinApplication(bool isMixinApplication) {
-    setModifier(Modifier.MIXIN_APPLICATION, isMixinApplication);
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters => _typeParameters;
-
-  /**
-   * Set the type parameters defined for this class to the given
-   * [typeParameters].
-   */
-  void set typeParameters(List<TypeParameterElement> typeParameters) {
-    for (TypeParameterElement typeParameter in typeParameters) {
-      (typeParameter as TypeParameterElementImpl).enclosingElement = this;
-    }
-    this._typeParameters = typeParameters;
-  }
-
-  @override
-  ConstructorElement get unnamedConstructor {
-    for (ConstructorElement element in constructors) {
-      String name = element.displayName;
-      if (name == null || name.isEmpty) {
-        return element;
-      }
-    }
-    return null;
-  }
-
-  /**
-   * Set whether this class is a valid mixin.
-   */
-  void set validMixin(bool isValidMixin) {
-    setModifier(Modifier.MIXIN, isValidMixin);
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitClassElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    String name = displayName;
-    if (name == null) {
-      buffer.write("{unnamed class}");
-    } else {
-      buffer.write(name);
-    }
-    int variableCount = _typeParameters.length;
-    if (variableCount > 0) {
-      buffer.write("<");
-      for (int i = 0; i < variableCount; i++) {
-        if (i > 0) {
-          buffer.write(", ");
-        }
-        (_typeParameters[i] as TypeParameterElementImpl).appendTo(buffer);
-      }
-      buffer.write(">");
-    }
-  }
-
-  @override
-  NamedCompilationUnitMember computeNode() {
-    if (isEnum) {
-      return getNodeMatching((node) => node is EnumDeclaration);
-    } else {
-      return getNodeMatching(
-          (node) => node is ClassDeclaration || node is ClassTypeAlias);
-    }
-  }
-
-  @override
-  ElementImpl getChild(String identifier) {
-    //
-    // The casts in this method are safe because the set methods would have
-    // thrown a CCE if any of the elements in the arrays were not of the
-    // expected types.
-    //
-    for (PropertyAccessorElement accessor in _accessors) {
-      if ((accessor as PropertyAccessorElementImpl).identifier == identifier) {
-        return accessor as PropertyAccessorElementImpl;
-      }
-    }
-    for (ConstructorElement constructor in _constructors) {
-      if ((constructor as ConstructorElementImpl).identifier == identifier) {
-        return constructor as ConstructorElementImpl;
-      }
-    }
-    for (FieldElement field in _fields) {
-      if ((field as FieldElementImpl).identifier == identifier) {
-        return field as FieldElementImpl;
-      }
-    }
-    for (MethodElement method in _methods) {
-      if ((method as MethodElementImpl).identifier == identifier) {
-        return method as MethodElementImpl;
-      }
-    }
-    for (TypeParameterElement typeParameter in _typeParameters) {
-      if ((typeParameter as TypeParameterElementImpl).identifier ==
-          identifier) {
-        return typeParameter as TypeParameterElementImpl;
-      }
-    }
-    return null;
-  }
-
-  @override
-  FieldElement getField(String name) {
-    for (FieldElement fieldElement in _fields) {
-      if (name == fieldElement.name) {
-        return fieldElement;
-      }
-    }
-    return null;
-  }
-
-  @override
-  PropertyAccessorElement getGetter(String getterName) {
-    for (PropertyAccessorElement accessor in _accessors) {
-      if (accessor.isGetter && accessor.name == getterName) {
-        return accessor;
-      }
-    }
-    return null;
-  }
-
-  @override
-  MethodElement getMethod(String methodName) {
-    for (MethodElement method in _methods) {
-      if (method.name == methodName) {
-        return method;
-      }
-    }
-    return null;
-  }
-
-  @override
-  ConstructorElement getNamedConstructor(String name) {
-    for (ConstructorElement element in constructors) {
-      String elementName = element.name;
-      if (elementName != null && elementName == name) {
-        return element;
-      }
-    }
-    return null;
-  }
-
-  @override
-  PropertyAccessorElement getSetter(String setterName) {
-    // TODO (jwren) revisit- should we append '=' here or require clients to
-    // include it?
-    // Do we need the check for isSetter below?
-    if (!StringUtilities.endsWithChar(setterName, 0x3D)) {
-      setterName += '=';
-    }
-    for (PropertyAccessorElement accessor in _accessors) {
-      if (accessor.isSetter && accessor.name == setterName) {
-        return accessor;
-      }
-    }
-    return null;
-  }
-
-  @override
-  bool isSuperConstructorAccessible(ConstructorElement constructor) {
-    // If this class has no mixins, then all superclass constructors are
-    // accessible.
-    if (mixins.isEmpty) {
-      return true;
-    }
-    // Otherwise only constructors that lack optional parameters are
-    // accessible (see dartbug.com/19576).
-    for (ParameterElement parameter in constructor.parameters) {
-      if (parameter.parameterKind != ParameterKind.REQUIRED) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  @override
-  MethodElement lookUpConcreteMethod(
-          String methodName, LibraryElement library) =>
-      _internalLookUpConcreteMethod(methodName, library, true);
-
-  @override
-  PropertyAccessorElement lookUpGetter(
-          String getterName, LibraryElement library) =>
-      _internalLookUpGetter(getterName, library, true);
-
-  @override
-  PropertyAccessorElement lookUpInheritedConcreteGetter(
-          String getterName, LibraryElement library) =>
-      _internalLookUpConcreteGetter(getterName, library, false);
-
-  @override
-  MethodElement lookUpInheritedConcreteMethod(
-          String methodName, LibraryElement library) =>
-      _internalLookUpConcreteMethod(methodName, library, false);
-
-  @override
-  PropertyAccessorElement lookUpInheritedConcreteSetter(
-          String setterName, LibraryElement library) =>
-      _internalLookUpConcreteSetter(setterName, library, false);
-
-  @override
-  MethodElement lookUpInheritedMethod(
-          String methodName, LibraryElement library) =>
-      _internalLookUpMethod(methodName, library, false);
-
-  @override
-  MethodElement lookUpMethod(String methodName, LibraryElement library) =>
-      _internalLookUpMethod(methodName, library, true);
-
-  @override
-  PropertyAccessorElement lookUpSetter(
-          String setterName, LibraryElement library) =>
-      _internalLookUpSetter(setterName, library, true);
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(_accessors, visitor);
-    safelyVisitChildren(_constructors, visitor);
-    safelyVisitChildren(_fields, visitor);
-    safelyVisitChildren(_methods, visitor);
-    safelyVisitChildren(_typeParameters, visitor);
-  }
-
-  void _collectAllSupertypes(List<InterfaceType> supertypes) {
-    List<InterfaceType> typesToVisit = new List<InterfaceType>();
-    List<ClassElement> visitedClasses = new List<ClassElement>();
-    typesToVisit.add(this.type);
-    while (!typesToVisit.isEmpty) {
-      InterfaceType currentType = typesToVisit.removeAt(0);
-      ClassElement currentElement = currentType.element;
-      if (!visitedClasses.contains(currentElement)) {
-        visitedClasses.add(currentElement);
-        if (!identical(currentType, this.type)) {
-          supertypes.add(currentType);
-        }
-        InterfaceType supertype = currentType.superclass;
-        if (supertype != null) {
-          typesToVisit.add(supertype);
-        }
-        for (InterfaceType type in currentElement.interfaces) {
-          typesToVisit.add(type);
-        }
-        for (InterfaceType type in currentElement.mixins) {
-          ClassElement element = type.element;
-          if (!visitedClasses.contains(element)) {
-            supertypes.add(type);
-          }
-        }
-      }
-    }
-  }
-
-  /**
-   * Compute a list of constructors for this class, which is a mixin
-   * application.  If specified, [visitedClasses] is a list of the other mixin
-   * application classes which have been visited on the way to reaching this
-   * one (this is used to detect circularities).
-   */
-  List<ConstructorElement> _computeMixinAppConstructors(
-      [List<ClassElementImpl> visitedClasses = null]) {
-    // First get the list of constructors of the superclass which need to be
-    // forwarded to this class.
-    Iterable<ConstructorElement> constructorsToForward;
-    if (supertype == null) {
-      // Shouldn't ever happen, since the only class with no supertype is
-      // Object, and it isn't a mixin application.  But for safety's sake just
-      // assume an empty list.
-      assert(false);
-      constructorsToForward = <ConstructorElement>[];
-    } else if (!supertype.element.isMixinApplication) {
-      List<ConstructorElement> superclassConstructors =
-          supertype.element.constructors;
-      // Filter out any constructors with optional parameters (see
-      // dartbug.com/15101).
-      constructorsToForward =
-          superclassConstructors.where(isSuperConstructorAccessible);
-    } else {
-      if (visitedClasses == null) {
-        visitedClasses = <ClassElementImpl>[this];
-      } else {
-        if (visitedClasses.contains(this)) {
-          // Loop in the class hierarchy.  Don't try to forward any
-          // constructors.
-          return <ConstructorElement>[];
-        }
-        visitedClasses.add(this);
-      }
-      try {
-        ClassElementImpl superclass = supertype.element;
-        constructorsToForward =
-            superclass._computeMixinAppConstructors(visitedClasses);
-      } finally {
-        visitedClasses.removeLast();
-      }
-    }
-
-    // Figure out the type parameter substitution we need to perform in order
-    // to produce constructors for this class.  We want to be robust in the
-    // face of errors, so drop any extra type arguments and fill in any missing
-    // ones with `dynamic`.
-    List<DartType> parameterTypes =
-        TypeParameterTypeImpl.getTypes(supertype.typeParameters);
-    List<DartType> argumentTypes = new List<DartType>.filled(
-        parameterTypes.length, DynamicTypeImpl.instance);
-    for (int i = 0; i < supertype.typeArguments.length; i++) {
-      if (i >= argumentTypes.length) {
-        break;
-      }
-      argumentTypes[i] = supertype.typeArguments[i];
-    }
-
-    // Now create an implicit constructor for every constructor found above,
-    // substituting type parameters as appropriate.
-    return constructorsToForward
-        .map((ConstructorElement superclassConstructor) {
-      ConstructorElementImpl implicitConstructor =
-          new ConstructorElementImpl(superclassConstructor.name, -1);
-      implicitConstructor.synthetic = true;
-      implicitConstructor.redirectedConstructor = superclassConstructor;
-      implicitConstructor.const2 = superclassConstructor.isConst;
-      implicitConstructor.returnType = type;
-      List<ParameterElement> superParameters = superclassConstructor.parameters;
-      int count = superParameters.length;
-      if (count > 0) {
-        List<ParameterElement> implicitParameters =
-            new List<ParameterElement>(count);
-        for (int i = 0; i < count; i++) {
-          ParameterElement superParameter = superParameters[i];
-          ParameterElementImpl implicitParameter =
-              new ParameterElementImpl(superParameter.name, -1);
-          implicitParameter.const3 = superParameter.isConst;
-          implicitParameter.final2 = superParameter.isFinal;
-          implicitParameter.parameterKind = superParameter.parameterKind;
-          implicitParameter.synthetic = true;
-          implicitParameter.type =
-              superParameter.type.substitute2(argumentTypes, parameterTypes);
-          implicitParameters[i] = implicitParameter;
-        }
-        implicitConstructor.parameters = implicitParameters;
-      }
-      FunctionTypeImpl constructorType =
-          new FunctionTypeImpl(implicitConstructor);
-      constructorType.typeArguments = type.typeArguments;
-      implicitConstructor.type = constructorType;
-      implicitConstructor.enclosingElement = this;
-      return implicitConstructor;
-    }).toList();
-  }
-
-  PropertyAccessorElement _internalLookUpConcreteGetter(
-      String getterName, LibraryElement library, bool includeThisClass) {
-    PropertyAccessorElement getter =
-        _internalLookUpGetter(getterName, library, includeThisClass);
-    while (getter != null && getter.isAbstract) {
-      Element definingClass = getter.enclosingElement;
-      if (definingClass is! ClassElementImpl) {
-        return null;
-      }
-      getter = (definingClass as ClassElementImpl)._internalLookUpGetter(
-          getterName, library, false);
-    }
-    return getter;
-  }
-
-  MethodElement _internalLookUpConcreteMethod(
-      String methodName, LibraryElement library, bool includeThisClass) {
-    MethodElement method =
-        _internalLookUpMethod(methodName, library, includeThisClass);
-    while (method != null && method.isAbstract) {
-      ClassElement definingClass = method.enclosingElement;
-      if (definingClass == null) {
-        return null;
-      }
-      method = definingClass.lookUpInheritedMethod(methodName, library);
-    }
-    return method;
-  }
-
-  PropertyAccessorElement _internalLookUpConcreteSetter(
-      String setterName, LibraryElement library, bool includeThisClass) {
-    PropertyAccessorElement setter =
-        _internalLookUpSetter(setterName, library, includeThisClass);
-    while (setter != null && setter.isAbstract) {
-      Element definingClass = setter.enclosingElement;
-      if (definingClass is! ClassElementImpl) {
-        return null;
-      }
-      setter = (definingClass as ClassElementImpl)._internalLookUpSetter(
-          setterName, library, false);
-    }
-    return setter;
-  }
-
-  PropertyAccessorElement _internalLookUpGetter(
-      String getterName, LibraryElement library, bool includeThisClass) {
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    ClassElement currentElement = this;
-    if (includeThisClass) {
-      PropertyAccessorElement element = currentElement.getGetter(getterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    while (currentElement != null && visitedClasses.add(currentElement)) {
-      for (InterfaceType mixin in currentElement.mixins.reversed) {
-        ClassElement mixinElement = mixin.element;
-        if (mixinElement != null) {
-          PropertyAccessorElement element = mixinElement.getGetter(getterName);
-          if (element != null && element.isAccessibleIn(library)) {
-            return element;
-          }
-        }
-      }
-      InterfaceType supertype = currentElement.supertype;
-      if (supertype == null) {
-        return null;
-      }
-      currentElement = supertype.element;
-      PropertyAccessorElement element = currentElement.getGetter(getterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    return null;
-  }
-
-  MethodElement _internalLookUpMethod(
-      String methodName, LibraryElement library, bool includeThisClass) {
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    ClassElement currentElement = this;
-    if (includeThisClass) {
-      MethodElement element = currentElement.getMethod(methodName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    while (currentElement != null && visitedClasses.add(currentElement)) {
-      for (InterfaceType mixin in currentElement.mixins.reversed) {
-        ClassElement mixinElement = mixin.element;
-        if (mixinElement != null) {
-          MethodElement element = mixinElement.getMethod(methodName);
-          if (element != null && element.isAccessibleIn(library)) {
-            return element;
-          }
-        }
-      }
-      InterfaceType supertype = currentElement.supertype;
-      if (supertype == null) {
-        return null;
-      }
-      currentElement = supertype.element;
-      MethodElement element = currentElement.getMethod(methodName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    return null;
-  }
-
-  PropertyAccessorElement _internalLookUpSetter(
-      String setterName, LibraryElement library, bool includeThisClass) {
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    ClassElement currentElement = this;
-    if (includeThisClass) {
-      PropertyAccessorElement element = currentElement.getSetter(setterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    while (currentElement != null && visitedClasses.add(currentElement)) {
-      for (InterfaceType mixin in currentElement.mixins.reversed) {
-        ClassElement mixinElement = mixin.element;
-        if (mixinElement != null) {
-          PropertyAccessorElement element = mixinElement.getSetter(setterName);
-          if (element != null && element.isAccessibleIn(library)) {
-            return element;
-          }
-        }
-      }
-      InterfaceType supertype = currentElement.supertype;
-      if (supertype == null) {
-        return null;
-      }
-      currentElement = supertype.element;
-      PropertyAccessorElement element = currentElement.getSetter(setterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    return null;
-  }
-
-  bool _safeIsOrInheritsProxy(
-      ClassElement classElt, HashSet<ClassElement> visitedClassElts) {
-    if (visitedClassElts.contains(classElt)) {
-      return false;
-    }
-    visitedClassElts.add(classElt);
-    if (classElt.isProxy) {
-      return true;
-    } else if (classElt.supertype != null &&
-        _safeIsOrInheritsProxy(classElt.supertype.element, visitedClassElts)) {
-      return true;
-    }
-    List<InterfaceType> supertypes = classElt.interfaces;
-    for (int i = 0; i < supertypes.length; i++) {
-      if (_safeIsOrInheritsProxy(supertypes[i].element, visitedClassElts)) {
-        return true;
-      }
-    }
-    supertypes = classElt.mixins;
-    for (int i = 0; i < supertypes.length; i++) {
-      if (_safeIsOrInheritsProxy(supertypes[i].element, visitedClassElts)) {
-        return true;
-      }
-    }
-    return false;
-  }
-}
-
-/**
- * An element that is contained within a [ClassElement].
- */
-abstract class ClassMemberElement implements Element {
-  /**
-   * Return the type in which this member is defined.
-   */
-  @override
-  ClassElement get enclosingElement;
-
-  /**
-   * Return `true` if this element is a static element. A static element is an
-   * element that is not associated with a particular instance, but rather with
-   * an entire library or class.
-   */
-  bool get isStatic;
-}
-
-/**
- * An element representing a compilation unit.
- */
-abstract class CompilationUnitElement implements Element, UriReferencedElement {
-  /**
-   * An empty list of compilation unit elements.
-   */
-  static const List<CompilationUnitElement> EMPTY_LIST =
-      const <CompilationUnitElement>[];
-
-  /**
-   * Return a list containing all of the top-level accessors (getters and
-   * setters) contained in this compilation unit.
-   */
-  List<PropertyAccessorElement> get accessors;
-
-  /**
-   * Return the library in which this compilation unit is defined.
-   */
-  @override
-  LibraryElement get enclosingElement;
-
-  /**
-   * Return a list containing all of the enums contained in this compilation
-   * unit.
-   */
-  List<ClassElement> get enums;
-
-  /**
-   * Return a list containing all of the top-level functions contained in this
-   * compilation unit.
-   */
-  List<FunctionElement> get functions;
-
-  /**
-   * Return a list containing all of the function type aliases contained in this
-   * compilation unit.
-   */
-  List<FunctionTypeAliasElement> get functionTypeAliases;
-
-  /**
-   * Return `true` if this compilation unit defines a top-level function named
-   * `loadLibrary`.
-   */
-  bool get hasLoadLibraryFunction;
-
-  /**
-   * Return a list containing all of the top-level variables contained in this
-   * compilation unit.
-   */
-  List<TopLevelVariableElement> get topLevelVariables;
-
-  /**
-   * Return a list containing all of the classes contained in this compilation
-   * unit.
-   */
-  List<ClassElement> get types;
-
-  /**
-   * Return the resolved [CompilationUnit] node that declares this element.
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  CompilationUnit computeNode();
-
-  /**
-   * Return the element at the given [offset], maybe `null` if no such element.
-   */
-  Element getElementAt(int offset);
-
-  /**
-   * Return the enum defined in this compilation unit that has the given [name],
-   * or `null` if this compilation unit does not define an enum with the given
-   * name.
-   */
-  ClassElement getEnum(String name);
-
-  /**
-   * Return the class defined in this compilation unit that has the given
-   * [name], or `null` if this compilation unit does not define a class with the
-   * given name.
-   */
-  ClassElement getType(String name);
-}
-
-/**
- * A concrete implementation of a [CompilationUnitElement].
- */
-class CompilationUnitElementImpl extends UriReferencedElementImpl
-    implements CompilationUnitElement {
-  /**
-   * An empty list of compilation unit elements.
-   */
-  @deprecated // Use CompilationUnitElement.EMPTY_LIST
-  static const List<CompilationUnitElement> EMPTY_ARRAY =
-      const <CompilationUnitElement>[];
-
-  /**
-   * The source that corresponds to this compilation unit.
-   */
-  Source source;
-
-  /**
-   * The source of the library containing this compilation unit.
-   *
-   * This is the same as the source of the containing [LibraryElement],
-   * except that it does not require the containing [LibraryElement] to be
-   * computed.
-   */
-  Source librarySource;
-
-  /**
-   * A list containing all of the top-level accessors (getters and setters)
-   * contained in this compilation unit.
-   */
-  List<PropertyAccessorElement> _accessors = PropertyAccessorElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the enums contained in this compilation unit.
-   */
-  List<ClassElement> _enums = ClassElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the top-level functions contained in this
-   * compilation unit.
-   */
-  List<FunctionElement> _functions = FunctionElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the function type aliases contained in this
-   * compilation unit.
-   */
-  List<FunctionTypeAliasElement> _typeAliases =
-      FunctionTypeAliasElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the types contained in this compilation unit.
-   */
-  List<ClassElement> _types = ClassElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the variables contained in this compilation unit.
-   */
-  List<TopLevelVariableElement> _variables = TopLevelVariableElement.EMPTY_LIST;
-
-  /**
-   * A map from offsets to elements of this unit at these offsets.
-   */
-  final Map<int, Element> _offsetToElementMap = new HashMap<int, Element>();
-
-  /**
-   * Initialize a newly created compilation unit element to have the given
-   * [name].
-   */
-  CompilationUnitElementImpl(String name) : super(name, -1);
-
-  @override
-  List<PropertyAccessorElement> get accessors => _accessors;
-
-  /**
-   * Set the top-level accessors (getters and setters) contained in this
-   * compilation unit to the given [accessors].
-   */
-  void set accessors(List<PropertyAccessorElement> accessors) {
-    for (PropertyAccessorElement accessor in accessors) {
-      (accessor as PropertyAccessorElementImpl).enclosingElement = this;
-    }
-    this._accessors = accessors;
-  }
-
-  @override
-  LibraryElement get enclosingElement =>
-      super.enclosingElement as LibraryElement;
-
-  @override
-  List<ClassElement> get enums => _enums;
-
-  /**
-   * Set the enums contained in this compilation unit to the given [enums].
-   */
-  void set enums(List<ClassElement> enums) {
-    for (ClassElement enumDeclaration in enums) {
-      (enumDeclaration as ClassElementImpl).enclosingElement = this;
-    }
-    this._enums = enums;
-  }
-
-  @override
-  List<FunctionElement> get functions => _functions;
-
-  /**
-   * Set the top-level functions contained in this compilation unit to the given
-   * [functions].
-   */
-  void set functions(List<FunctionElement> functions) {
-    for (FunctionElement function in functions) {
-      (function as FunctionElementImpl).enclosingElement = this;
-    }
-    this._functions = functions;
-  }
-
-  @override
-  List<FunctionTypeAliasElement> get functionTypeAliases => _typeAliases;
-
-  @override
-  int get hashCode => source.hashCode;
-
-  @override
-  bool get hasLoadLibraryFunction {
-    for (int i = 0; i < _functions.length; i++) {
-      if (_functions[i].name == FunctionElement.LOAD_LIBRARY_NAME) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  String get identifier => source.encoding;
-
-  @override
-  ElementKind get kind => ElementKind.COMPILATION_UNIT;
-
-  @override
-  List<TopLevelVariableElement> get topLevelVariables => _variables;
-
-  /**
-   * Set the top-level variables contained in this compilation unit to the given
-   * [variables].
-   */
-  void set topLevelVariables(List<TopLevelVariableElement> variables) {
-    for (TopLevelVariableElement field in variables) {
-      (field as TopLevelVariableElementImpl).enclosingElement = this;
-    }
-    this._variables = variables;
-  }
-
-  /**
-   * Set the function type aliases contained in this compilation unit to the
-   * given [typeAliases].
-   */
-  void set typeAliases(List<FunctionTypeAliasElement> typeAliases) {
-    for (FunctionTypeAliasElement typeAlias in typeAliases) {
-      (typeAlias as FunctionTypeAliasElementImpl).enclosingElement = this;
-    }
-    this._typeAliases = typeAliases;
-  }
-
-  @override
-  List<ClassElement> get types => _types;
-
-  /**
-   * Set the types contained in this compilation unit to the given [types].
-   */
-  void set types(List<ClassElement> types) {
-    for (ClassElement type in types) {
-      (type as ClassElementImpl).enclosingElement = this;
-    }
-    this._types = types;
-  }
-
-  @override
-  bool operator ==(Object object) =>
-      object is CompilationUnitElementImpl && source == object.source;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitCompilationUnitElement(this);
-
-  /**
-   * This method is invoked after this unit was incrementally resolved.
-   */
-  void afterIncrementalResolution() {
-    _offsetToElementMap.clear();
-  }
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    if (source == null) {
-      buffer.write("{compilation unit}");
-    } else {
-      buffer.write(source.fullName);
-    }
-  }
-
-  @override
-  CompilationUnit computeNode() => unit;
-
-  @override
-  ElementImpl getChild(String identifier) {
-    //
-    // The casts in this method are safe because the set methods would have
-    // thrown a CCE if any of the elements in the arrays were not of the
-    // expected types.
-    //
-    for (PropertyAccessorElement accessor in _accessors) {
-      if ((accessor as PropertyAccessorElementImpl).identifier == identifier) {
-        return accessor as PropertyAccessorElementImpl;
-      }
-    }
-    for (VariableElement variable in _variables) {
-      if ((variable as VariableElementImpl).identifier == identifier) {
-        return variable as VariableElementImpl;
-      }
-    }
-    for (ExecutableElement function in _functions) {
-      if ((function as ExecutableElementImpl).identifier == identifier) {
-        return function as ExecutableElementImpl;
-      }
-    }
-    for (FunctionTypeAliasElement typeAlias in _typeAliases) {
-      if ((typeAlias as FunctionTypeAliasElementImpl).identifier ==
-          identifier) {
-        return typeAlias as FunctionTypeAliasElementImpl;
-      }
-    }
-    for (ClassElement type in _types) {
-      if ((type as ClassElementImpl).identifier == identifier) {
-        return type as ClassElementImpl;
-      }
-    }
-    for (ClassElement type in _enums) {
-      if ((type as ClassElementImpl).identifier == identifier) {
-        return type as ClassElementImpl;
-      }
-    }
-    return null;
-  }
-
-  @override
-  Element getElementAt(int offset) {
-    if (_offsetToElementMap.isEmpty) {
-      accept(new _BuildOffsetToElementMap(_offsetToElementMap));
-    }
-    return _offsetToElementMap[offset];
-  }
-
-  @override
-  ClassElement getEnum(String enumName) {
-    for (ClassElement enumDeclaration in _enums) {
-      if (enumDeclaration.name == enumName) {
-        return enumDeclaration;
-      }
-    }
-    return null;
-  }
-
-  @override
-  ClassElement getType(String className) {
-    for (ClassElement type in _types) {
-      if (type.name == className) {
-        return type;
-      }
-    }
-    return null;
-  }
-
-  /**
-   * Replace the given [from] top-level variable with [to] in this compilation unit.
-   */
-  void replaceTopLevelVariable(
-      TopLevelVariableElement from, TopLevelVariableElement to) {
-    int index = _variables.indexOf(from);
-    _variables[index] = to;
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(_accessors, visitor);
-    safelyVisitChildren(_enums, visitor);
-    safelyVisitChildren(_functions, visitor);
-    safelyVisitChildren(_typeAliases, visitor);
-    safelyVisitChildren(_types, visitor);
-    safelyVisitChildren(_variables, visitor);
-  }
-}
-
-/**
- * A [FieldElement] for a 'const' or 'final' field that has an initializer.
- *
- * TODO(paulberry): we should rename this class to reflect the fact that it's
- * used for both const and final fields.  However, we shouldn't do so until
- * we've created an API for reading the values of constants; until that API is
- * available, clients are likely to read constant values by casting to
- * ConstFieldElementImpl, so it would be a breaking change to rename this
- * class.
- */
-class ConstFieldElementImpl extends FieldElementImpl with ConstVariableElement {
-  /**
-   * The result of evaluating this variable's initializer.
-   */
-  EvaluationResultImpl _result;
-
-  /**
-   * Initialize a newly created synthetic field element to have the given
-   * [name] and [offset].
-   */
-  ConstFieldElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created field element to have the given [name].
-   */
-  @deprecated // Use new ConstFieldElementImpl.forNode(name)
-  ConstFieldElementImpl.con1(Identifier name) : super.forNode(name);
-
-  /**
-   * Initialize a newly created synthetic field element to have the given
-   * [name] and [offset].
-   */
-  @deprecated // Use new ConstFieldElementImpl(name, offset)
-  ConstFieldElementImpl.con2(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created field element to have the given [name].
-   */
-  ConstFieldElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  EvaluationResultImpl get evaluationResult => _result;
-
-  @override
-  void set evaluationResult(EvaluationResultImpl result) {
-    this._result = result;
-  }
-}
-
-/**
- * A [LocalVariableElement] for a local 'const' variable that has an
- * initializer.
- */
-class ConstLocalVariableElementImpl extends LocalVariableElementImpl
-    with ConstVariableElement {
-  /**
-   * The result of evaluating this variable's initializer.
-   */
-  EvaluationResultImpl _result;
-
-  /**
-   * Initialize a newly created local variable element to have the given [name]
-   * and [offset].
-   */
-  ConstLocalVariableElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created local variable element to have the given [name].
-   */
-  ConstLocalVariableElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  EvaluationResultImpl get evaluationResult => _result;
-
-  @override
-  void set evaluationResult(EvaluationResultImpl result) {
-    this._result = result;
-  }
-}
-
-/**
- * An element representing a constructor or a factory method defined within a
- * class.
- */
-abstract class ConstructorElement
-    implements ClassMemberElement, ExecutableElement, ConstantEvaluationTarget {
-  /**
-   * An empty list of constructor elements.
-   */
-  static const List<ConstructorElement> EMPTY_LIST =
-      const <ConstructorElement>[];
-
-  /**
-   * Return `true` if this constructor is a const constructor.
-   */
-  bool get isConst;
-
-  /**
-   * Return `true` if this constructor can be used as a default constructor -
-   * unnamed and has no required parameters.
-   */
-  bool get isDefaultConstructor;
-
-  /**
-   * Return `true` if this constructor represents a factory constructor.
-   */
-  bool get isFactory;
-
-  /**
-   * Return the offset of the character immediately following the last character
-   * of this constructor's name, or `null` if not named.
-   */
-  int get nameEnd;
-
-  /**
-   * Return the offset of the `.` before this constructor name, or `null` if
-   * not named.
-   */
-  int get periodOffset;
-
-  /**
-   * Return the constructor to which this constructor is redirecting, or `null`
-   * if this constructor does not redirect to another constructor or if the
-   * library containing this constructor has not yet been resolved.
-   */
-  ConstructorElement get redirectedConstructor;
-
-  /**
-   * Return the resolved [ConstructorDeclaration] node that declares this
-   * [ConstructorElement] .
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  ConstructorDeclaration computeNode();
-}
-
-/**
- * A concrete implementation of a [ConstructorElement].
- */
-class ConstructorElementImpl extends ExecutableElementImpl
-    implements ConstructorElement {
-  /**
-   * An empty list of constructor elements.
-   */
-  @deprecated // Use ConstructorElement.EMPTY_LIST
-  static const List<ConstructorElement> EMPTY_ARRAY =
-      const <ConstructorElement>[];
-
-  /**
-   * The constructor to which this constructor is redirecting.
-   */
-  ConstructorElement redirectedConstructor;
-
-  /**
-   * The initializers for this constructor (used for evaluating constant
-   * instance creation expressions).
-   */
-  List<ConstructorInitializer> constantInitializers;
-
-  /**
-   * The offset of the `.` before this constructor name or `null` if not named.
-   */
-  int periodOffset;
-
-  /**
-   * Return the offset of the character immediately following the last character
-   * of this constructor's name, or `null` if not named.
-   */
-  int nameEnd;
-
-  /**
-   * True if this constructor has been found by constant evaluation to be free
-   * of redirect cycles, and is thus safe to evaluate.
-   */
-  bool isCycleFree = false;
-
-  /**
-   * Initialize a newly created constructor element to have the given [name] and
-   * [offset].
-   */
-  ConstructorElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created constructor element to have the given [name].
-   */
-  ConstructorElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Set whether this constructor represents a 'const' constructor.
-   */
-  void set const2(bool isConst) {
-    setModifier(Modifier.CONST, isConst);
-  }
-
-  @override
-  ClassElement get enclosingElement => super.enclosingElement as ClassElement;
-
-  /**
-   * Set whether this constructor represents a factory method.
-   */
-  void set factory(bool isFactory) {
-    setModifier(Modifier.FACTORY, isFactory);
-  }
-
-  @override
-  bool get isConst => hasModifier(Modifier.CONST);
-
-  @override
-  bool get isDefaultConstructor {
-    // unnamed
-    String name = this.name;
-    if (name != null && name.length != 0) {
-      return false;
-    }
-    // no required parameters
-    for (ParameterElement parameter in parameters) {
-      if (parameter.parameterKind == ParameterKind.REQUIRED) {
-        return false;
-      }
-    }
-    // OK, can be used as default constructor
-    return true;
-  }
-
-  @override
-  bool get isFactory => hasModifier(Modifier.FACTORY);
-
-  @override
-  bool get isStatic => false;
-
-  @override
-  ElementKind get kind => ElementKind.CONSTRUCTOR;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitConstructorElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    if (enclosingElement == null) {
-      String message;
-      String name = displayName;
-      if (name != null && !name.isEmpty) {
-        message =
-            'Found constructor element named $name with no enclosing element';
-      } else {
-        message = 'Found unnamed constructor element with no enclosing element';
-      }
-      AnalysisEngine.instance.logger.logError(message);
-      buffer.write('<unknown class>');
-    } else {
-      buffer.write(enclosingElement.displayName);
-    }
-    String name = displayName;
-    if (name != null && !name.isEmpty) {
-      buffer.write(".");
-      buffer.write(name);
-    }
-    super.appendTo(buffer);
-  }
-
-  @override
-  ConstructorDeclaration computeNode() =>
-      getNodeMatching((node) => node is ConstructorDeclaration);
-}
-
-/**
- * A constructor element defined in a parameterized type where the values of the
- * type parameters are known.
- */
-class ConstructorMember extends ExecutableMember implements ConstructorElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  ConstructorMember(ConstructorElement baseElement, InterfaceType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  ConstructorElement get baseElement => super.baseElement as ConstructorElement;
-
-  @override
-  InterfaceType get definingType => super.definingType as InterfaceType;
-
-  @override
-  ClassElement get enclosingElement => baseElement.enclosingElement;
-
-  @override
-  bool get isConst => baseElement.isConst;
-
-  @override
-  bool get isDefaultConstructor => baseElement.isDefaultConstructor;
-
-  @override
-  bool get isFactory => baseElement.isFactory;
-
-  @override
-  int get nameEnd => baseElement.nameEnd;
-
-  @override
-  int get periodOffset => baseElement.periodOffset;
-
-  @override
-  ConstructorElement get redirectedConstructor =>
-      from(baseElement.redirectedConstructor, definingType);
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitConstructorElement(this);
-
-  @override
-  ConstructorDeclaration computeNode() => baseElement.computeNode();
-
-  @override
-  String toString() {
-    ConstructorElement baseElement = this.baseElement;
-    List<ParameterElement> parameters = this.parameters;
-    FunctionType type = this.type;
-    StringBuffer buffer = new StringBuffer();
-    buffer.write(baseElement.enclosingElement.displayName);
-    String name = displayName;
-    if (name != null && !name.isEmpty) {
-      buffer.write(".");
-      buffer.write(name);
-    }
-    buffer.write("(");
-    int parameterCount = parameters.length;
-    for (int i = 0; i < parameterCount; i++) {
-      if (i > 0) {
-        buffer.write(", ");
-      }
-      buffer.write(parameters[i]);
-    }
-    buffer.write(")");
-    if (type != null) {
-      buffer.write(Element.RIGHT_ARROW);
-      buffer.write(type.returnType);
-    }
-    return buffer.toString();
-  }
-
-  /**
-   * If the given [constructor]'s type is different when any type parameters
-   * from the defining type's declaration are replaced with the actual type
-   * arguments from the [definingType], create a constructor member representing
-   * the given constructor. Return the member that was created, or the original
-   * constructor if no member was created.
-   */
-  static ConstructorElement from(
-      ConstructorElement constructor, InterfaceType definingType) {
-    if (constructor == null || definingType.typeArguments.length == 0) {
-      return constructor;
-    }
-    FunctionType baseType = constructor.type;
-    if (baseType == null) {
-      // TODO(brianwilkerson) We need to understand when this can happen.
-      return constructor;
-    }
-    List<DartType> argumentTypes = definingType.typeArguments;
-    List<DartType> parameterTypes = definingType.element.type.typeArguments;
-    FunctionType substitutedType =
-        baseType.substitute2(argumentTypes, parameterTypes);
-    if (baseType == substitutedType) {
-      return constructor;
-    }
-    // TODO(brianwilkerson) Consider caching the substituted type in the
-    // instance. It would use more memory but speed up some operations.
-    // We need to see how often the type is being re-computed.
-    return new ConstructorMember(constructor, definingType);
-  }
-}
-
-/**
- * A [TopLevelVariableElement] for a top-level 'const' variable that has an
- * initializer.
- */
-class ConstTopLevelVariableElementImpl extends TopLevelVariableElementImpl
-    with ConstVariableElement {
-  /**
-   * The result of evaluating this variable's initializer.
-   */
-  EvaluationResultImpl _result;
-
-  /**
-   * Initialize a newly created top-level variable element to have the given
-   * [name].
-   */
-  ConstTopLevelVariableElementImpl(Identifier name) : super.forNode(name);
-
-  @override
-  EvaluationResultImpl get evaluationResult => _result;
-
-  @override
-  void set evaluationResult(EvaluationResultImpl result) {
-    this._result = result;
-  }
-}
-
-/**
- * Mixin used by elements that represent constant variables and have
- * initializers.
- *
- * Note that in correct Dart code, all constant variables must have
- * initializers.  However, analyzer also needs to handle incorrect Dart code,
- * in which case there might be some constant variables that lack initializers.
- * This interface is only used for constant variables that have initializers.
- *
- * This class is not intended to be part of the public API for analyzer.
- */
-abstract class ConstVariableElement implements PotentiallyConstVariableElement {
-  /**
-   * If this element represents a constant variable, and it has an initializer,
-   * a copy of the initializer for the constant.  Otherwise `null`.
-   *
-   * Note that in correct Dart code, all constant variables must have
-   * initializers.  However, analyzer also needs to handle incorrect Dart code,
-   * in which case there might be some constant variables that lack
-   * initializers.
-   */
-  Expression constantInitializer;
-}
-
-/**
- * The type associated with elements in the element model.
- */
-abstract class DartType {
-  /**
-   * An empty list of types.
-   */
-  static const List<DartType> EMPTY_LIST = const <DartType>[];
-
-  /**
-   * Return the name of this type as it should appear when presented to users in
-   * contexts such as error messages.
-   */
-  String get displayName;
-
-  /**
-   * Return the element representing the declaration of this type, or `null` if
-   * the type has not, or cannot, be associated with an element. The former case
-   * will occur if the element model is not yet complete; the latter case will
-   * occur if this object represents an undefined type.
-   */
-  Element get element;
-
-  /**
-   * Return `true` if this type represents the bottom type.
-   */
-  bool get isBottom;
-
-  /**
-   * Return `true` if this type represents the type 'Function' defined in the
-   * dart:core library.
-   */
-  bool get isDartCoreFunction;
-
-  /**
-   * Return `true` if this type represents the type 'dynamic'.
-   */
-  bool get isDynamic;
-
-  /**
-   * Return `true` if this type represents the type 'Object'.
-   */
-  bool get isObject;
-
-  /**
-   * Return `true` if this type represents a typename that couldn't be resolved.
-   */
-  bool get isUndefined;
-
-  /**
-   * Return `true` if this type represents the type 'void'.
-   */
-  bool get isVoid;
-
-  /**
-   * Return the name of this type, or `null` if the type does not have a name,
-   * such as when the type represents the type of an unnamed function.
-   */
-  String get name;
-
-  /**
-   * Return the least upper bound of this type and the given [type], or `null`
-   * if there is no least upper bound.
-   *
-   * Deprecated, since it is impossible to implement the correct algorithm
-   * without access to a [TypeProvider].  Please use
-   * [TypeSystem.getLeastUpperBound] instead.
-   */
-  @deprecated
-  DartType getLeastUpperBound(DartType type);
-
-  /**
-   * Return `true` if this type is assignable to the given [type]. A type
-   * <i>T</i> may be assigned to a type <i>S</i>, written <i>T</i> &hArr;
-   * <i>S</i>, iff either <i>T</i> <: <i>S</i> or <i>S</i> <: <i>T</i>.
-   */
-  bool isAssignableTo(DartType type);
-
-  /**
-   * Return `true` if this type is more specific than the given [type].
-   */
-  bool isMoreSpecificThan(DartType type);
-
-  /**
-   * Return `true` if this type is a subtype of the given [type].
-   */
-  bool isSubtypeOf(DartType type);
-
-  /**
-   * Return `true` if this type is a supertype of the given [type]. A type
-   * <i>S</i> is a supertype of <i>T</i>, written <i>S</i> :> <i>T</i>, iff
-   * <i>T</i> is a subtype of <i>S</i>.
-   */
-  bool isSupertypeOf(DartType type);
-
-  /**
-   * Return the type resulting from substituting the given [argumentTypes] for
-   * the given [parameterTypes] in this type. The specification defines this
-   * operation in section 2:
-   * <blockquote>
-   * The notation <i>[x<sub>1</sub>, ..., x<sub>n</sub>/y<sub>1</sub>, ...,
-   * y<sub>n</sub>]E</i> denotes a copy of <i>E</i> in which all occurrences of
-   * <i>y<sub>i</sub>, 1 <= i <= n</i> have been replaced with
-   * <i>x<sub>i</sub></i>.
-   * </blockquote>
-   * Note that, contrary to the specification, this method will not create a
-   * copy of this type if no substitutions were required, but will return this
-   * type directly.
-   *
-   * Note too that the current implementation of this method is only guaranteed
-   * to work when the parameter types are type variables.
-   */
-  DartType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes);
-}
-
-/**
- * A [FieldFormalParameterElementImpl] for parameters that have an initializer.
- */
-class DefaultFieldFormalParameterElementImpl
-    extends FieldFormalParameterElementImpl with ConstVariableElement {
-  /**
-   * The result of evaluating this variable's initializer.
-   */
-  EvaluationResultImpl _result;
-
-  /**
-   * Initialize a newly created parameter element to have the given [name].
-   */
-  DefaultFieldFormalParameterElementImpl(Identifier name) : super(name);
-
-  @override
-  EvaluationResultImpl get evaluationResult => _result;
-
-  @override
-  void set evaluationResult(EvaluationResultImpl result) {
-    this._result = result;
-  }
-}
-
-/**
- * A [ParameterElement] for parameters that have an initializer.
- */
-class DefaultParameterElementImpl extends ParameterElementImpl
-    with ConstVariableElement {
-  /**
-   * The result of evaluating this variable's initializer.
-   */
-  EvaluationResultImpl _result;
-
-  /**
-   * Initialize a newly created parameter element to have the given [name].
-   */
-  DefaultParameterElementImpl(Identifier name) : super.forNode(name);
-
-  @override
-  EvaluationResultImpl get evaluationResult => _result;
-
-  @override
-  void set evaluationResult(EvaluationResultImpl result) {
-    this._result = result;
-  }
-
-  @override
-  DefaultFormalParameter computeNode() =>
-      getNodeMatching((node) => node is DefaultFormalParameter);
-}
-
-/**
- * The synthetic element representing the declaration of the type `dynamic`.
- */
-class DynamicElementImpl extends ElementImpl implements TypeDefiningElement {
-  /**
-   * Return the unique instance of this class.
-   */
-  static DynamicElementImpl get instance =>
-      DynamicTypeImpl.instance.element as DynamicElementImpl;
-
-  @override
-  DynamicTypeImpl type;
-
-  /**
-   * Initialize a newly created instance of this class. Instances of this class
-   * should <b>not</b> be created except as part of creating the type associated
-   * with this element. The single instance of this class should be accessed
-   * through the method [getInstance].
-   */
-  DynamicElementImpl() : super(Keyword.DYNAMIC.syntax, -1) {
-    setModifier(Modifier.SYNTHETIC, true);
-  }
-
-  @override
-  ElementKind get kind => ElementKind.DYNAMIC;
-
-  @override
-  accept(ElementVisitor visitor) => null;
-}
-
-/**
- * The [Type] representing the type `dynamic`.
- */
-class DynamicTypeImpl extends TypeImpl {
-  /**
-   * The unique instance of this class.
-   */
-  static DynamicTypeImpl _INSTANCE = new DynamicTypeImpl._();
-
-  /**
-   * Return the unique instance of this class.
-   */
-  static DynamicTypeImpl get instance => _INSTANCE;
-
-  /**
-   * Prevent the creation of instances of this class.
-   */
-  DynamicTypeImpl._()
-      : super(new DynamicElementImpl(), Keyword.DYNAMIC.syntax) {
-    (element as DynamicElementImpl).type = this;
-  }
-
-  /**
-   * Constructor used by [CircularTypeImpl].
-   */
-  DynamicTypeImpl._circular()
-      : super(_INSTANCE.element, Keyword.DYNAMIC.syntax);
-
-  @override
-  int get hashCode => 1;
-
-  @override
-  bool get isDynamic => true;
-
-  @override
-  bool operator ==(Object object) => identical(object, this);
-
-  @override
-  bool isMoreSpecificThan(DartType type,
-      [bool withDynamic = false, Set<Element> visitedElements]) {
-    // T is S
-    if (identical(this, type)) {
-      return true;
-    }
-    // else
-    return withDynamic;
-  }
-
-  @override
-  bool isSubtypeOf(DartType type) => true;
-
-  @override
-  bool isSupertypeOf(DartType type) => true;
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) => this;
-
-  @override
-  DartType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) {
-    int length = parameterTypes.length;
-    for (int i = 0; i < length; i++) {
-      if (parameterTypes[i] == this) {
-        return argumentTypes[i];
-      }
-    }
-    return this;
-  }
-}
-
-/**
- * The base class for all of the elements in the element model. Generally
- * speaking, the element model is a semantic model of the program that
- * represents things that are declared with a name and hence can be referenced
- * elsewhere in the code.
- *
- * There are two exceptions to the general case. First, there are elements in
- * the element model that are created for the convenience of various kinds of
- * analysis but that do not have any corresponding declaration within the source
- * code. Such elements are marked as being <i>synthetic</i>. Examples of
- * synthetic elements include
- * * default constructors in classes that do not define any explicit
- *   constructors,
- * * getters and setters that are induced by explicit field declarations,
- * * fields that are induced by explicit declarations of getters and setters,
- *   and
- * * functions representing the initialization expression for a variable.
- *
- * Second, there are elements in the element model that do not have a name.
- * These correspond to unnamed functions and exist in order to more accurately
- * represent the semantic structure of the program.
- */
-abstract class Element implements AnalysisTarget {
-  /**
-   * An Unicode right arrow.
-   */
-  static final String RIGHT_ARROW = " \u2192 ";
-
-  /**
-   * A comparator that can be used to sort elements by their name offset.
-   * Elements with a smaller offset will be sorted to be before elements with a
-   * larger name offset.
-   */
-  static final Comparator<Element> SORT_BY_OFFSET = (Element firstElement,
-          Element secondElement) =>
-      firstElement.nameOffset - secondElement.nameOffset;
-
-  /**
-   * Return the analysis context in which this element is defined.
-   */
-  AnalysisContext get context;
-
-  /**
-   * Return the display name of this element, or `null` if this element does not
-   * have a name.
-   *
-   * In most cases the name and the display name are the same. Differences
-   * though are cases such as setters where the name of some setter `set f(x)`
-   * is `f=`, instead of `f`.
-   */
-  String get displayName;
-
-  /**
-   * Return the element that either physically or logically encloses this
-   * element. This will be `null` if this element is a library because libraries
-   * are the top-level elements in the model.
-   */
-  Element get enclosingElement;
-
-  /**
-   * The unique integer identifier of this element.
-   */
-  int get id;
-
-  /**
-   * Return `true` if this element has an annotation of the form '@deprecated'
-   * or '@Deprecated('..')'.
-   */
-  bool get isDeprecated;
-
-  /**
-   * Return `true` if this element has an annotation of the form '@override'.
-   */
-  bool get isOverride;
-
-  /**
-   * Return `true` if this element is private. Private elements are visible only
-   * within the library in which they are declared.
-   */
-  bool get isPrivate;
-
-  /**
-   * Return `true` if this element is public. Public elements are visible within
-   * any library that imports the library in which they are declared.
-   */
-  bool get isPublic;
-
-  /**
-   * Return `true` if this element is synthetic. A synthetic element is an
-   * element that is not represented in the source code explicitly, but is
-   * implied by the source code, such as the default constructor for a class
-   * that does not explicitly define any constructors.
-   */
-  bool get isSynthetic;
-
-  /**
-   * Return the kind of element that this is.
-   */
-  ElementKind get kind;
-
-  /**
-   * Return the library that contains this element. This will be the element
-   * itself if it is a library element. This will be `null` if this element is
-   * an HTML file because HTML files are not contained in libraries.
-   */
-  LibraryElement get library;
-
-  /**
-   * Return an object representing the location of this element in the element
-   * model. The object can be used to locate this element at a later time.
-   */
-  ElementLocation get location;
-
-  /**
-   * Return a list containing all of the metadata associated with this element.
-   * The array will be empty if the element does not have any metadata or if the
-   * library containing this element has not yet been resolved.
-   */
-  List<ElementAnnotation> get metadata;
-
-  /**
-   * Return the name of this element, or `null` if this element does not have a
-   * name.
-   */
-  String get name;
-
-  /**
-   * Return the offset of the name of this element in the file that contains the
-   * declaration of this element, or `-1` if this element is synthetic, does not
-   * have a name, or otherwise does not have an offset.
-   */
-  int get nameOffset;
-
-  /**
-   * Return the resolved [AstNode] node that declares this element, or `null` if
-   * this element is synthetic or isn't contained in a compilation unit, such as
-   * a [LibraryElement].
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   *
-   * <b>Note:</b> This method cannot be used in an async environment.
-   */
-  @deprecated
-  AstNode get node;
-
-  /**
-   * Return the source that contains this element, or `null` if this element is
-   * not contained in a source.
-   */
-  Source get source;
-
-  /**
-   * Return the resolved [CompilationUnit] that declares this element, or `null`
-   * if this element is synthetic.
-   *
-   * This method is expensive, because resolved AST might have been already
-   * evicted from cache, so parsing and resolving will be performed.
-   */
-  CompilationUnit get unit;
-
-  /**
-   * Use the given [visitor] to visit this element. Return the value returned by
-   * the visitor as a result of visiting this element.
-   */
-  accept(ElementVisitor visitor);
-
-  /**
-   * Return the documentation comment for this element as it appears in the
-   * original source (complete with the beginning and ending delimiters), or
-   * `null` if this element does not have a documentation comment associated
-   * with it. This can be a long-running operation if the information needed to
-   * access the comment is not cached.
-   *
-   * Throws [AnalysisException] if the documentation comment could not be
-   * determined because the analysis could not be performed
-   */
-  String computeDocumentationComment();
-
-  /**
-   * Return the resolved [AstNode] node that declares this element, or `null` if
-   * this element is synthetic or isn't contained in a compilation unit, such as
-   * a [LibraryElement].
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   *
-   * <b>Note:</b> This method cannot be used in an async environment.
-   */
-  AstNode computeNode();
-
-  /**
-   * Return the most immediate ancestor of this element for which the
-   * [predicate] returns `true`, or `null` if there is no such ancestor. Note
-   * that this element will never be returned.
-   */
-  Element getAncestor(Predicate<Element> predicate);
-
-  /**
-   * Return a display name for the given element that includes the path to the
-   * compilation unit in which the type is defined. If [shortName] is `null`
-   * then [getDisplayName] will be used as the name of this element. Otherwise
-   * the provided name will be used.
-   */
-  // TODO(brianwilkerson) Make the parameter optional.
-  String getExtendedDisplayName(String shortName);
-
-  /**
-   * Return `true` if this element, assuming that it is within scope, is
-   * accessible to code in the given [library]. This is defined by the Dart
-   * Language Specification in section 3.2:
-   * <blockquote>
-   * A declaration <i>m</i> is accessible to library <i>L</i> if <i>m</i> is
-   * declared in <i>L</i> or if <i>m</i> is public.
-   * </blockquote>
-   */
-  bool isAccessibleIn(LibraryElement library);
-
-  /**
-   * Use the given [visitor] to visit all of the children of this element. There
-   * is no guarantee of the order in which the children will be visited.
-   */
-  void visitChildren(ElementVisitor visitor);
-}
-
-/**
- * A single annotation associated with an element.
- */
-abstract class ElementAnnotation {
-  /**
-   * An empty list of annotations.
-   */
-  static const List<ElementAnnotation> EMPTY_LIST = const <ElementAnnotation>[];
-
-  /**
-   * Return the element representing the field, variable, or const constructor
-   * being used as an annotation.
-   */
-  Element get element;
-
-  /**
-   * Return `true` if this annotation marks the associated element as being
-   * deprecated.
-   */
-  bool get isDeprecated;
-
-  /**
-   * Return `true` if this annotation marks the associated method as being
-   * expected to override an inherited method.
-   */
-  bool get isOverride;
-
-  /**
-   * Return `true` if this annotation marks the associated class as implementing
-   * a proxy object.
-   */
-  bool get isProxy;
-}
-
-/**
- * A concrete implementation of an [ElementAnnotation].
- */
-class ElementAnnotationImpl implements ElementAnnotation {
-  /**
-   * An empty list of annotations.
-   */
-  @deprecated // Use ElementAnnotation.EMPTY_LIST
-  static const List<ElementAnnotationImpl> EMPTY_ARRAY =
-      const <ElementAnnotationImpl>[];
-
-  /**
-   * The name of the class used to mark an element as being deprecated.
-   */
-  static String _DEPRECATED_CLASS_NAME = "Deprecated";
-
-  /**
-   * The name of the top-level variable used to mark an element as being
-   * deprecated.
-   */
-  static String _DEPRECATED_VARIABLE_NAME = "deprecated";
-
-  /**
-   * The name of the top-level variable used to mark a method as being expected
-   * to override an inherited method.
-   */
-  static String _OVERRIDE_VARIABLE_NAME = "override";
-
-  /**
-   * The name of the top-level variable used to mark a class as implementing a
-   * proxy object.
-   */
-  static String PROXY_VARIABLE_NAME = "proxy";
-
-  /**
-   * The element representing the field, variable, or constructor being used as
-   * an annotation.
-   */
-  final Element element;
-
-  /**
-   * The result of evaluating this annotation as a compile-time constant
-   * expression, or `null` if the compilation unit containing the variable has
-   * not been resolved.
-   */
-  EvaluationResultImpl evaluationResult;
-
-  /**
-   * Initialize a newly created annotation. The given [element] is the element
-   * representing the field, variable, or constructor being used as an
-   * annotation.
-   */
-  ElementAnnotationImpl(this.element);
-
-  @override
-  bool get isDeprecated {
-    if (element != null) {
-      LibraryElement library = element.library;
-      if (library != null && library.isDartCore) {
-        if (element is ConstructorElement) {
-          ConstructorElement constructorElement = element as ConstructorElement;
-          if (constructorElement.enclosingElement.name ==
-              _DEPRECATED_CLASS_NAME) {
-            return true;
-          }
-        } else if (element is PropertyAccessorElement &&
-            element.name == _DEPRECATED_VARIABLE_NAME) {
-          return true;
-        }
-      }
-    }
-    return false;
-  }
-
-  @override
-  bool get isOverride {
-    if (element != null) {
-      LibraryElement library = element.library;
-      if (library != null && library.isDartCore) {
-        if (element is PropertyAccessorElement &&
-            element.name == _OVERRIDE_VARIABLE_NAME) {
-          return true;
-        }
-      }
-    }
-    return false;
-  }
-
-  @override
-  bool get isProxy {
-    if (element != null) {
-      LibraryElement library = element.library;
-      if (library != null && library.isDartCore) {
-        if (element is PropertyAccessorElement &&
-            element.name == PROXY_VARIABLE_NAME) {
-          return true;
-        }
-      }
-    }
-    return false;
-  }
-
-  @override
-  String toString() => '@$element';
-}
-
-/**
- * A base class for concrete implementations of an [Element].
- */
-abstract class ElementImpl implements Element {
-  static int _NEXT_ID = 0;
-
-  final int id = _NEXT_ID++;
-
-  /**
-   * The enclosing element of this element, or `null` if this element is at the
-   * root of the element structure.
-   */
-  ElementImpl _enclosingElement;
-
-  /**
-   * The name of this element.
-   */
-  String _name;
-
-  /**
-   * The offset of the name of this element in the file that contains the
-   * declaration of this element.
-   */
-  int _nameOffset = 0;
-
-  /**
-   * A bit-encoded form of the modifiers associated with this element.
-   */
-  int _modifiers = 0;
-
-  /**
-   * A list containing all of the metadata associated with this element.
-   */
-  List<ElementAnnotation> metadata = ElementAnnotation.EMPTY_LIST;
-
-  /**
-   * A cached copy of the calculated hashCode for this element.
-   */
-  int _cachedHashCode;
-
-  /**
-   * A cached copy of the calculated location for this element.
-   */
-  ElementLocation _cachedLocation;
-
-  /**
-   * Initialize a newly created element to have the given [name] at the given
-   * [_nameOffset].
-   */
-  ElementImpl(String name, this._nameOffset) {
-    this._name = StringUtilities.intern(name);
-  }
-
-  /**
-   * Initialize a newly created element to have the given [name].
-   */
-  ElementImpl.forNode(Identifier name)
-      : this(name == null ? "" : name.name, name == null ? -1 : name.offset);
-
-  @override
-  AnalysisContext get context {
-    if (_enclosingElement == null) {
-      return null;
-    }
-    return _enclosingElement.context;
-  }
-
-  @override
-  String get displayName => _name;
-
-  @override
-  Element get enclosingElement => _enclosingElement;
-
-  /**
-   * Set the enclosing element of this element to the given [element].
-   */
-  void set enclosingElement(Element element) {
-    _enclosingElement = element as ElementImpl;
-    _cachedLocation = null;
-    _cachedHashCode = null;
-  }
-
-  @override
-  int get hashCode {
-    // TODO: We might want to re-visit this optimization in the future.
-    // We cache the hash code value as this is a very frequently called method.
-    if (_cachedHashCode == null) {
-      int hashIdentifier = identifier.hashCode;
-      Element enclosing = enclosingElement;
-      if (enclosing != null) {
-        _cachedHashCode = hashIdentifier + enclosing.hashCode;
-      } else {
-        _cachedHashCode = hashIdentifier;
-      }
-    }
-    return _cachedHashCode;
-  }
-
-  /**
-   * Return an identifier that uniquely identifies this element among the
-   * children of this element's parent.
-   */
-  String get identifier => name;
-
-  @override
-  bool get isDeprecated {
-    for (ElementAnnotation annotation in metadata) {
-      if (annotation.isDeprecated) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  bool get isOverride {
-    for (ElementAnnotation annotation in metadata) {
-      if (annotation.isOverride) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  bool get isPrivate {
-    String name = displayName;
-    if (name == null) {
-      return true;
-    }
-    return Identifier.isPrivateName(name);
-  }
-
-  @override
-  bool get isPublic => !isPrivate;
-
-  @override
-  bool get isSynthetic => hasModifier(Modifier.SYNTHETIC);
-
-  @override
-  LibraryElement get library =>
-      getAncestor((element) => element is LibraryElement);
-
-  @override
-  ElementLocation get location {
-    if (_cachedLocation == null) {
-      _cachedLocation = new ElementLocationImpl.con1(this);
-    }
-    return _cachedLocation;
-  }
-
-  @override
-  String get name => _name;
-
-  void set name(String name) {
-    this._name = name;
-    _cachedLocation = null;
-    _cachedHashCode = null;
-  }
-
-  /**
-   * The offset of the name of this element in the file that contains the
-   * declaration of this element.
-   */
-  int get nameOffset => _nameOffset;
-
-  /**
-   * Sets the offset of the name of this element in the file that contains the
-   * declaration of this element.
-   */
-  void set nameOffset(int offset) {
-    _nameOffset = offset;
-    _cachedHashCode = null;
-    _cachedLocation = null;
-  }
-
-  @deprecated
-  @override
-  AstNode get node => computeNode();
-
-  @override
-  Source get source {
-    if (_enclosingElement == null) {
-      return null;
-    }
-    return _enclosingElement.source;
-  }
-
-  /**
-   * Set whether this element is synthetic.
-   */
-  void set synthetic(bool isSynthetic) {
-    setModifier(Modifier.SYNTHETIC, isSynthetic);
-  }
-
-  @override
-  CompilationUnit get unit => context.resolveCompilationUnit(source, library);
-
-  @override
-  bool operator ==(Object object) {
-    if (identical(this, object)) {
-      return true;
-    }
-    if (object == null || hashCode != object.hashCode) {
-      return false;
-    }
-    return object.runtimeType == runtimeType &&
-        (object as Element).location == location;
-  }
-
-  /**
-   * Append a textual representation of this element to the given [buffer].
-   */
-  void appendTo(StringBuffer buffer) {
-    if (_name == null) {
-      buffer.write("<unnamed ");
-      buffer.write(runtimeType.toString());
-      buffer.write(">");
-    } else {
-      buffer.write(_name);
-    }
-  }
-
-  @override
-  String computeDocumentationComment() {
-    AnalysisContext context = this.context;
-    if (context == null) {
-      return null;
-    }
-    return context.computeDocumentationComment(this);
-  }
-
-  @override
-  AstNode computeNode() => getNodeMatching((node) => node is AstNode);
-
-  /**
-   * Set this element as the enclosing element for given [element].
-   */
-  void encloseElement(ElementImpl element) {
-    element.enclosingElement = this;
-  }
-
-  @override
-  Element getAncestor(Predicate<Element> predicate) {
-    Element ancestor = _enclosingElement;
-    while (ancestor != null && !predicate(ancestor)) {
-      ancestor = ancestor.enclosingElement;
-    }
-    return ancestor;
-  }
-
-  /**
-   * Return the child of this element that is uniquely identified by the given
-   * [identifier], or `null` if there is no such child.
-   */
-  ElementImpl getChild(String identifier) => null;
-
-  @override
-  String getExtendedDisplayName(String shortName) {
-    if (shortName == null) {
-      shortName = displayName;
-    }
-    Source source = this.source;
-    if (source != null) {
-      return "$shortName (${source.fullName})";
-    }
-    return shortName;
-  }
-
-  /**
-   * Return the resolved [AstNode] of the given type enclosing [getNameOffset].
-   */
-  AstNode getNodeMatching(Predicate<AstNode> predicate) {
-    CompilationUnit unit = this.unit;
-    if (unit == null) {
-      return null;
-    }
-    int offset = nameOffset;
-    AstNode node = new NodeLocator(offset).searchWithin(unit);
-    if (node == null) {
-      return null;
-    }
-    return node.getAncestor(predicate);
-  }
-
-  /**
-   * Return `true` if this element has the given [modifier] associated with it.
-   */
-  bool hasModifier(Modifier modifier) =>
-      BooleanArray.getEnum(_modifiers, modifier);
-
-  @override
-  bool isAccessibleIn(LibraryElement library) {
-    if (Identifier.isPrivateName(_name)) {
-      return library == this.library;
-    }
-    return true;
-  }
-
-  /**
-   * If the given [child] is not `null`, use the given [visitor] to visit it.
-   */
-  void safelyVisitChild(Element child, ElementVisitor visitor) {
-    if (child != null) {
-      child.accept(visitor);
-    }
-  }
-
-  /**
-   * Use the given [visitor] to visit all of the [children] in the given array.
-   */
-  void safelyVisitChildren(List<Element> children, ElementVisitor visitor) {
-    if (children != null) {
-      for (Element child in children) {
-        child.accept(visitor);
-      }
-    }
-  }
-
-  /**
-   * Set whether the given [modifier] is associated with this element to
-   * correspond to the given [value].
-   */
-  void setModifier(Modifier modifier, bool value) {
-    _modifiers = BooleanArray.setEnum(_modifiers, modifier, value);
-  }
-
-  @override
-  String toString() {
-    StringBuffer buffer = new StringBuffer();
-    appendTo(buffer);
-    return buffer.toString();
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    // There are no children to visit
-  }
-}
-
-/**
- * The enumeration `ElementKind` defines the various kinds of elements in the
- * element model.
- */
-class ElementKind extends Enum<ElementKind> {
-  static const ElementKind CLASS = const ElementKind('CLASS', 0, "class");
-
-  static const ElementKind COMPILATION_UNIT =
-      const ElementKind('COMPILATION_UNIT', 1, "compilation unit");
-
-  static const ElementKind CONSTRUCTOR =
-      const ElementKind('CONSTRUCTOR', 2, "constructor");
-
-  static const ElementKind DYNAMIC =
-      const ElementKind('DYNAMIC', 3, "<dynamic>");
-
-  static const ElementKind EMBEDDED_HTML_SCRIPT =
-      const ElementKind('EMBEDDED_HTML_SCRIPT', 4, "embedded html script");
-
-  static const ElementKind ERROR = const ElementKind('ERROR', 5, "<error>");
-
-  static const ElementKind EXPORT =
-      const ElementKind('EXPORT', 6, "export directive");
-
-  static const ElementKind EXTERNAL_HTML_SCRIPT =
-      const ElementKind('EXTERNAL_HTML_SCRIPT', 7, "external html script");
-
-  static const ElementKind FIELD = const ElementKind('FIELD', 8, "field");
-
-  static const ElementKind FUNCTION =
-      const ElementKind('FUNCTION', 9, "function");
-
-  static const ElementKind GETTER = const ElementKind('GETTER', 10, "getter");
-
-  static const ElementKind HTML = const ElementKind('HTML', 11, "html");
-
-  static const ElementKind IMPORT =
-      const ElementKind('IMPORT', 12, "import directive");
-
-  static const ElementKind LABEL = const ElementKind('LABEL', 13, "label");
-
-  static const ElementKind LIBRARY =
-      const ElementKind('LIBRARY', 14, "library");
-
-  static const ElementKind LOCAL_VARIABLE =
-      const ElementKind('LOCAL_VARIABLE', 15, "local variable");
-
-  static const ElementKind METHOD = const ElementKind('METHOD', 16, "method");
-
-  static const ElementKind NAME = const ElementKind('NAME', 17, "<name>");
-
-  static const ElementKind PARAMETER =
-      const ElementKind('PARAMETER', 18, "parameter");
-
-  static const ElementKind PREFIX =
-      const ElementKind('PREFIX', 19, "import prefix");
-
-  static const ElementKind SETTER = const ElementKind('SETTER', 20, "setter");
-
-  static const ElementKind TOP_LEVEL_VARIABLE =
-      const ElementKind('TOP_LEVEL_VARIABLE', 21, "top level variable");
-
-  static const ElementKind FUNCTION_TYPE_ALIAS =
-      const ElementKind('FUNCTION_TYPE_ALIAS', 22, "function type alias");
-
-  static const ElementKind TYPE_PARAMETER =
-      const ElementKind('TYPE_PARAMETER', 23, "type parameter");
-
-  static const ElementKind UNIVERSE =
-      const ElementKind('UNIVERSE', 24, "<universe>");
-
-  static const List<ElementKind> values = const [
-    CLASS,
-    COMPILATION_UNIT,
-    CONSTRUCTOR,
-    DYNAMIC,
-    EMBEDDED_HTML_SCRIPT,
-    ERROR,
-    EXPORT,
-    EXTERNAL_HTML_SCRIPT,
-    FIELD,
-    FUNCTION,
-    GETTER,
-    HTML,
-    IMPORT,
-    LABEL,
-    LIBRARY,
-    LOCAL_VARIABLE,
-    METHOD,
-    NAME,
-    PARAMETER,
-    PREFIX,
-    SETTER,
-    TOP_LEVEL_VARIABLE,
-    FUNCTION_TYPE_ALIAS,
-    TYPE_PARAMETER,
-    UNIVERSE
-  ];
-
-  /**
-   * The name displayed in the UI for this kind of element.
-   */
-  final String displayName;
-
-  /**
-   * Initialize a newly created element kind to have the given [displayName].
-   */
-  const ElementKind(String name, int ordinal, this.displayName)
-      : super(name, ordinal);
-
-  /**
-   * Return the kind of the given [element], or [ERROR] if the element is
-   * `null`. This is a utility method that can reduce the need for null checks
-   * in other places.
-   */
-  static ElementKind of(Element element) {
-    if (element == null) {
-      return ERROR;
-    }
-    return element.kind;
-  }
-}
-
-/**
- * The location of an element within the element model.
- */
-abstract class ElementLocation {
-  /**
-   * Return the path to the element whose location is represented by this
-   * object. Clients must not modify the returned array.
-   */
-  List<String> get components;
-
-  /**
-   * Return an encoded representation of this location that can be used to
-   * create a location that is equal to this location.
-   */
-  String get encoding;
-}
-
-/**
- * A concrete implementation of an [ElementLocation].
- */
-class ElementLocationImpl implements ElementLocation {
-  /**
-   * The character used to separate components in the encoded form.
-   */
-  static int _SEPARATOR_CHAR = 0x3B;
-
-  /**
-   * The path to the element whose location is represented by this object.
-   */
-  List<String> _components;
-
-  /**
-   * The object managing [indexKeyId] and [indexLocationId].
-   */
-  Object indexOwner;
-
-  /**
-   * A cached id of this location in index.
-   */
-  int indexKeyId;
-
-  /**
-   * A cached id of this location in index.
-   */
-  int indexLocationId;
-
-  /**
-   * Initialize a newly created location to represent the given [element].
-   */
-  ElementLocationImpl.con1(Element element) {
-    List<String> components = new List<String>();
-    Element ancestor = element;
-    while (ancestor != null) {
-      components.insert(0, (ancestor as ElementImpl).identifier);
-      ancestor = ancestor.enclosingElement;
-    }
-    this._components = components;
-  }
-
-  /**
-   * Initialize a newly created location from the given [encoding].
-   */
-  ElementLocationImpl.con2(String encoding) {
-    this._components = _decode(encoding);
-  }
-
-  /**
-   * Initialize a newly created location from the given [components].
-   */
-  ElementLocationImpl.con3(List<String> components) {
-    this._components = components;
-  }
-
-  @override
-  List<String> get components => _components;
-
-  @override
-  String get encoding {
-    StringBuffer buffer = new StringBuffer();
-    int length = _components.length;
-    for (int i = 0; i < length; i++) {
-      if (i > 0) {
-        buffer.writeCharCode(_SEPARATOR_CHAR);
-      }
-      _encode(buffer, _components[i]);
-    }
-    return buffer.toString();
-  }
-
-  @override
-  int get hashCode {
-    int result = 1;
-    for (int i = 0; i < _components.length; i++) {
-      String component = _components[i];
-      result = 31 * result + component.hashCode;
-    }
-    return result;
-  }
-
-  @override
-  bool operator ==(Object object) {
-    if (identical(this, object)) {
-      return true;
-    }
-    if (object is! ElementLocationImpl) {
-      return false;
-    }
-    ElementLocationImpl location = object as ElementLocationImpl;
-    List<String> otherComponents = location._components;
-    int length = _components.length;
-    if (otherComponents.length != length) {
-      return false;
-    }
-    for (int i = 0; i < length; i++) {
-      if (_components[i] != otherComponents[i]) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  @override
-  String toString() => encoding;
-
-  /**
-   * Decode the [encoding] of a location into a list of components and return
-   * the components.
-   */
-  List<String> _decode(String encoding) {
-    List<String> components = new List<String>();
-    StringBuffer buffer = new StringBuffer();
-    int index = 0;
-    int length = encoding.length;
-    while (index < length) {
-      int currentChar = encoding.codeUnitAt(index);
-      if (currentChar == _SEPARATOR_CHAR) {
-        if (index + 1 < length &&
-            encoding.codeUnitAt(index + 1) == _SEPARATOR_CHAR) {
-          buffer.writeCharCode(_SEPARATOR_CHAR);
-          index += 2;
-        } else {
-          components.add(buffer.toString());
-          buffer = new StringBuffer();
-          index++;
-        }
-      } else {
-        buffer.writeCharCode(currentChar);
-        index++;
-      }
-    }
-    components.add(buffer.toString());
-    return components;
-  }
-
-  /**
-   * Append an encoded form of the given [component] to the given [buffer].
-   */
-  void _encode(StringBuffer buffer, String component) {
-    int length = component.length;
-    for (int i = 0; i < length; i++) {
-      int currentChar = component.codeUnitAt(i);
-      if (currentChar == _SEPARATOR_CHAR) {
-        buffer.writeCharCode(_SEPARATOR_CHAR);
-      }
-      buffer.writeCharCode(currentChar);
-    }
-  }
-}
-
-/**
- * An object that can be used to visit an element structure.
- */
-abstract class ElementVisitor<R> {
-  R visitClassElement(ClassElement element);
-
-  R visitCompilationUnitElement(CompilationUnitElement element);
-
-  R visitConstructorElement(ConstructorElement element);
-
-  @deprecated
-  R visitEmbeddedHtmlScriptElement(EmbeddedHtmlScriptElement element);
-
-  R visitExportElement(ExportElement element);
-
-  @deprecated
-  R visitExternalHtmlScriptElement(ExternalHtmlScriptElement element);
-
-  R visitFieldElement(FieldElement element);
-
-  R visitFieldFormalParameterElement(FieldFormalParameterElement element);
-
-  R visitFunctionElement(FunctionElement element);
-
-  R visitFunctionTypeAliasElement(FunctionTypeAliasElement element);
-
-  @deprecated
-  R visitHtmlElement(HtmlElement element);
-
-  R visitImportElement(ImportElement element);
-
-  R visitLabelElement(LabelElement element);
-
-  R visitLibraryElement(LibraryElement element);
-
-  R visitLocalVariableElement(LocalVariableElement element);
-
-  R visitMethodElement(MethodElement element);
-
-  R visitMultiplyDefinedElement(MultiplyDefinedElement element);
-
-  R visitParameterElement(ParameterElement element);
-
-  R visitPrefixElement(PrefixElement element);
-
-  R visitPropertyAccessorElement(PropertyAccessorElement element);
-
-  R visitTopLevelVariableElement(TopLevelVariableElement element);
-
-  R visitTypeParameterElement(TypeParameterElement element);
-}
-
-/**
- * A script tag in an HTML file having content that defines a Dart library.
- */
-@deprecated
-abstract class EmbeddedHtmlScriptElement implements HtmlScriptElement {
-  /**
-   * Return the library element defined by the content of the script tag.
-   */
-  LibraryElement get scriptLibrary;
-}
-
-/**
- * A concrete implementation of an [EmbeddedHtmlScriptElement].
- */
-@deprecated
-class EmbeddedHtmlScriptElementImpl extends HtmlScriptElementImpl
-    implements EmbeddedHtmlScriptElement {
-  /**
-   * The library defined by the script tag's content.
-   */
-  LibraryElement _scriptLibrary;
-
-  /**
-   * Initialize a newly created script element to represent the given [node].
-   */
-  EmbeddedHtmlScriptElementImpl(XmlTagNode node) : super(node);
-
-  @override
-  ElementKind get kind => ElementKind.EMBEDDED_HTML_SCRIPT;
-
-  @override
-  LibraryElement get scriptLibrary => _scriptLibrary;
-
-  /**
-   * Set the script library defined by the script tag's content to the given
-   * [library].
-   */
-  void set scriptLibrary(LibraryElementImpl library) {
-    library.enclosingElement = this;
-    _scriptLibrary = library;
-  }
-
-  @override
-  accept(ElementVisitor visitor) =>
-      visitor.visitEmbeddedHtmlScriptElement(this);
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    safelyVisitChild(_scriptLibrary, visitor);
-  }
-}
-
-/**
- * An element representing an executable object, including functions, methods,
- * constructors, getters, and setters.
- */
-abstract class ExecutableElement implements Element {
-  /**
-   * An empty list of executable elements.
-   */
-  static const List<ExecutableElement> EMPTY_LIST = const <ExecutableElement>[];
-
-  /**
-   * Return a list containing all of the functions defined within this
-   * executable element.
-   */
-  List<FunctionElement> get functions;
-
-  /**
-   * Return `true` if this executable element is abstract. Executable elements
-   * are abstract if they are not external and have no body.
-   */
-  bool get isAbstract;
-
-  /**
-   * Return `true` if this executable element has body marked as being
-   * asynchronous.
-   */
-  bool get isAsynchronous;
-
-  /**
-   * Return `true` if this executable element is external. Executable elements
-   * are external if they are explicitly marked as such using the 'external'
-   * keyword.
-   */
-  bool get isExternal;
-
-  /**
-   * Return `true` if this executable element has a body marked as being a
-   * generator.
-   */
-  bool get isGenerator;
-
-  /**
-   * Return `true` if this executable element is an operator. The test may be
-   * based on the name of the executable element, in which case the result will
-   * be correct when the name is legal.
-   */
-  bool get isOperator;
-
-  /**
-   * Return `true` if this element is a static element. A static element is an
-   * element that is not associated with a particular instance, but rather with
-   * an entire library or class.
-   */
-  bool get isStatic;
-
-  /**
-   * Return `true` if this executable element has a body marked as being
-   * synchronous.
-   */
-  bool get isSynchronous;
-
-  /**
-   * Return a list containing all of the labels defined within this executable
-   * element.
-   */
-  List<LabelElement> get labels;
-
-  /**
-   * Return a list containing all of the local variables defined within this
-   * executable element.
-   */
-  List<LocalVariableElement> get localVariables;
-
-  /**
-   * Return a list containing all of the parameters defined by this executable
-   * element.
-   */
-  List<ParameterElement> get parameters;
-
-  /**
-   * Return the return type defined by this executable element.
-   */
-  DartType get returnType;
-
-  /**
-   * Return the type of function defined by this executable element.
-   */
-  FunctionType get type;
-
-  /**
-   * Return a list containing all of the type parameters defined for this
-   * executable element.
-   */
-  List<TypeParameterElement> get typeParameters;
-}
-
-/**
- * A base class for concrete implementations of an [ExecutableElement].
- */
-abstract class ExecutableElementImpl extends ElementImpl
-    implements ExecutableElement {
-  /**
-   * An empty list of executable elements.
-   */
-  @deprecated // Use ExecutableElement.EMPTY_LIST
-  static const List<ExecutableElement> EMPTY_ARRAY =
-      const <ExecutableElement>[];
-
-  /**
-   * A list containing all of the functions defined within this executable
-   * element.
-   */
-  List<FunctionElement> _functions = FunctionElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the labels defined within this executable element.
-   */
-  List<LabelElement> _labels = LabelElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the local variables defined within this executable
-   * element.
-   */
-  List<LocalVariableElement> _localVariables = LocalVariableElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the parameters defined by this executable element.
-   */
-  List<ParameterElement> _parameters = ParameterElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the type parameters defined for this executable
-   * element.
-   */
-  List<TypeParameterElement> _typeParameters = TypeParameterElement.EMPTY_LIST;
-
-  /**
-   * The return type defined by this executable element.
-   */
-  DartType returnType;
-
-  /**
-   * The type of function defined by this executable element.
-   */
-  FunctionType type;
-
-  /**
-   * Initialize a newly created executable element to have the given [name] and
-   * [offset].
-   */
-  ExecutableElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created executable element to have the given [name].
-   */
-  ExecutableElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Set whether this executable element's body is asynchronous.
-   */
-  void set asynchronous(bool isAsynchronous) {
-    setModifier(Modifier.ASYNCHRONOUS, isAsynchronous);
-  }
-
-  /**
-   * Set whether this executable element is external.
-   */
-  void set external(bool isExternal) {
-    setModifier(Modifier.EXTERNAL, isExternal);
-  }
-
-  @override
-  List<FunctionElement> get functions => _functions;
-
-  /**
-   * Set the functions defined within this executable element to the given
-   * [functions].
-   */
-  void set functions(List<FunctionElement> functions) {
-    for (FunctionElement function in functions) {
-      (function as FunctionElementImpl).enclosingElement = this;
-    }
-    this._functions = functions;
-  }
-
-  /**
-   * Set whether this method's body is a generator.
-   */
-  void set generator(bool isGenerator) {
-    setModifier(Modifier.GENERATOR, isGenerator);
-  }
-
-  @override
-  bool get isAbstract => hasModifier(Modifier.ABSTRACT);
-
-  @override
-  bool get isAsynchronous => hasModifier(Modifier.ASYNCHRONOUS);
-
-  @override
-  bool get isExternal => hasModifier(Modifier.EXTERNAL);
-
-  @override
-  bool get isGenerator => hasModifier(Modifier.GENERATOR);
-
-  @override
-  bool get isOperator => false;
-
-  @override
-  bool get isSynchronous => !hasModifier(Modifier.ASYNCHRONOUS);
-
-  @override
-  List<LabelElement> get labels => _labels;
-
-  /**
-   * Set the labels defined within this executable element to the given
-   * [labels].
-   */
-  void set labels(List<LabelElement> labels) {
-    for (LabelElement label in labels) {
-      (label as LabelElementImpl).enclosingElement = this;
-    }
-    this._labels = labels;
-  }
-
-  @override
-  List<LocalVariableElement> get localVariables => _localVariables;
-
-  /**
-   * Set the local variables defined within this executable element to the given
-   * [variables].
-   */
-  void set localVariables(List<LocalVariableElement> variables) {
-    for (LocalVariableElement variable in variables) {
-      (variable as LocalVariableElementImpl).enclosingElement = this;
-    }
-    this._localVariables = variables;
-  }
-
-  @override
-  List<ParameterElement> get parameters => _parameters;
-
-  /**
-   * Set the parameters defined by this executable element to the given
-   * [parameters].
-   */
-  void set parameters(List<ParameterElement> parameters) {
-    for (ParameterElement parameter in parameters) {
-      (parameter as ParameterElementImpl).enclosingElement = this;
-    }
-    this._parameters = parameters;
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters => _typeParameters;
-
-  /**
-   * Set the type parameters defined by this executable element to the given
-   * [typeParameters].
-   */
-  void set typeParameters(List<TypeParameterElement> typeParameters) {
-    for (TypeParameterElement parameter in typeParameters) {
-      (parameter as TypeParameterElementImpl).enclosingElement = this;
-    }
-    this._typeParameters = typeParameters;
-  }
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    if (this.kind != ElementKind.GETTER) {
-      int typeParameterCount = _typeParameters.length;
-      if (typeParameterCount > 0) {
-        buffer.write('<');
-        for (int i = 0; i < typeParameterCount; i++) {
-          if (i > 0) {
-            buffer.write(", ");
-          }
-          (_typeParameters[i] as TypeParameterElementImpl).appendTo(buffer);
-        }
-        buffer.write('>');
-      }
-      buffer.write("(");
-      String closing = null;
-      ParameterKind kind = ParameterKind.REQUIRED;
-      int parameterCount = _parameters.length;
-      for (int i = 0; i < parameterCount; i++) {
-        if (i > 0) {
-          buffer.write(", ");
-        }
-        ParameterElementImpl parameter = _parameters[i] as ParameterElementImpl;
-        ParameterKind parameterKind = parameter.parameterKind;
-        if (parameterKind != kind) {
-          if (closing != null) {
-            buffer.write(closing);
-          }
-          if (parameterKind == ParameterKind.POSITIONAL) {
-            buffer.write("[");
-            closing = "]";
-          } else if (parameterKind == ParameterKind.NAMED) {
-            buffer.write("{");
-            closing = "}";
-          } else {
-            closing = null;
-          }
-        }
-        kind = parameterKind;
-        parameter.appendToWithoutDelimiters(buffer);
-      }
-      if (closing != null) {
-        buffer.write(closing);
-      }
-      buffer.write(")");
-    }
-    if (type != null) {
-      buffer.write(Element.RIGHT_ARROW);
-      buffer.write(type.returnType);
-    }
-  }
-
-  @override
-  ElementImpl getChild(String identifier) {
-    for (ExecutableElement function in _functions) {
-      if ((function as ExecutableElementImpl).identifier == identifier) {
-        return function as ExecutableElementImpl;
-      }
-    }
-    for (LabelElement label in _labels) {
-      if ((label as LabelElementImpl).identifier == identifier) {
-        return label as LabelElementImpl;
-      }
-    }
-    for (VariableElement variable in _localVariables) {
-      if ((variable as VariableElementImpl).identifier == identifier) {
-        return variable as VariableElementImpl;
-      }
-    }
-    for (ParameterElement parameter in _parameters) {
-      if ((parameter as ParameterElementImpl).identifier == identifier) {
-        return parameter as ParameterElementImpl;
-      }
-    }
-    return null;
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(_functions, visitor);
-    safelyVisitChildren(_labels, visitor);
-    safelyVisitChildren(_localVariables, visitor);
-    safelyVisitChildren(_parameters, visitor);
-  }
-}
-
-/**
- * An executable element defined in a parameterized type where the values of the
- * type parameters are known.
- */
-abstract class ExecutableMember extends Member implements ExecutableElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  ExecutableMember(ExecutableElement baseElement, InterfaceType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  ExecutableElement get baseElement => super.baseElement as ExecutableElement;
-
-  @override
-  List<FunctionElement> get functions {
-    //
-    // Elements within this element should have type parameters substituted,
-    // just like this element.
-    //
-    throw new UnsupportedOperationException();
-//    return getBaseElement().getFunctions();
-  }
-
-  @override
-  bool get isAbstract => baseElement.isAbstract;
-
-  @override
-  bool get isAsynchronous => baseElement.isAsynchronous;
-
-  @override
-  bool get isExternal => baseElement.isExternal;
-
-  @override
-  bool get isGenerator => baseElement.isGenerator;
-
-  @override
-  bool get isOperator => baseElement.isOperator;
-
-  @override
-  bool get isStatic => baseElement.isStatic;
-
-  @override
-  bool get isSynchronous => baseElement.isSynchronous;
-
-  @override
-  List<LabelElement> get labels => baseElement.labels;
-
-  @override
-  List<LocalVariableElement> get localVariables {
-    //
-    // Elements within this element should have type parameters substituted,
-    // just like this element.
-    //
-    throw new UnsupportedOperationException();
-//    return getBaseElement().getLocalVariables();
-  }
-
-  @override
-  List<ParameterElement> get parameters {
-    List<ParameterElement> baseParameters = baseElement.parameters;
-    int parameterCount = baseParameters.length;
-    if (parameterCount == 0) {
-      return baseParameters;
-    }
-    List<ParameterElement> parameterizedParameters =
-        new List<ParameterElement>(parameterCount);
-    for (int i = 0; i < parameterCount; i++) {
-      parameterizedParameters[i] =
-          ParameterMember.from(baseParameters[i], definingType);
-    }
-    return parameterizedParameters;
-  }
-
-  @override
-  DartType get returnType => substituteFor(baseElement.returnType);
-
-  @override
-  FunctionType get type => substituteFor(baseElement.type);
-
-  @override
-  List<TypeParameterElement> get typeParameters => baseElement.typeParameters;
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    // TODO(brianwilkerson) We need to finish implementing the accessors used
-    // below so that we can safely invoke them.
-    super.visitChildren(visitor);
-    safelyVisitChildren(baseElement.functions, visitor);
-    safelyVisitChildren(labels, visitor);
-    safelyVisitChildren(baseElement.localVariables, visitor);
-    safelyVisitChildren(parameters, visitor);
-  }
-}
-
-/**
- * An export directive within a library.
- */
-abstract class ExportElement implements Element, UriReferencedElement {
-  /**
-   * An empty list of export elements.
-   */
-  @deprecated // Use ExportElement.EMPTY_LIST
-  static const List<ExportElement> EMPTY_ARRAY = const <ExportElement>[];
-
-  /**
-   * An empty list of export elements.
-   */
-  static const List<ExportElement> EMPTY_LIST = const <ExportElement>[];
-
-  /**
-   * Return a list containing the combinators that were specified as part of the
-   * export directive in the order in which they were specified.
-   */
-  List<NamespaceCombinator> get combinators;
-
-  /**
-   * Return the library that is exported from this library by this export
-   * directive.
-   */
-  LibraryElement get exportedLibrary;
-}
-
-/**
- * A concrete implementation of an [ExportElement].
- */
-class ExportElementImpl extends UriReferencedElementImpl
-    implements ExportElement {
-  /**
-   * The library that is exported from this library by this export directive.
-   */
-  LibraryElement exportedLibrary;
-
-  /**
-   * The combinators that were specified as part of the export directive in the
-   * order in which they were specified.
-   */
-  List<NamespaceCombinator> combinators = NamespaceCombinator.EMPTY_LIST;
-
-  /**
-   * Initialize a newly created export element at the given [offset].
-   */
-  ExportElementImpl(int offset) : super(null, offset);
-
-  @override
-  String get identifier => exportedLibrary.name;
-
-  @override
-  ElementKind get kind => ElementKind.EXPORT;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitExportElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write("export ");
-    (exportedLibrary as LibraryElementImpl).appendTo(buffer);
-  }
-}
-
-/**
- * A script tag in an HTML file having a `source` attribute that references a
- * Dart library source file.
- */
-@deprecated
-abstract class ExternalHtmlScriptElement implements HtmlScriptElement {
-  /**
-   * Return the source referenced by this element, or `null` if this element
-   * does not reference a Dart library source file.
-   */
-  Source get scriptSource;
-}
-
-/**
- * A concrete implementation of an [ExternalHtmlScriptElement].
- */
-@deprecated
-class ExternalHtmlScriptElementImpl extends HtmlScriptElementImpl
-    implements ExternalHtmlScriptElement {
-  /**
-   * The source specified in the `source` attribute or `null` if unspecified.
-   */
-  Source scriptSource;
-
-  /**
-   * Initialize a newly created script element to correspond to the given
-   * [node].
-   */
-  ExternalHtmlScriptElementImpl(XmlTagNode node) : super(node);
-
-  @override
-  ElementKind get kind => ElementKind.EXTERNAL_HTML_SCRIPT;
-
-  @override
-  accept(ElementVisitor visitor) =>
-      visitor.visitExternalHtmlScriptElement(this);
-}
-
-/**
- * A field defined within a type.
- */
-abstract class FieldElement
-    implements ClassMemberElement, PropertyInducingElement {
-  /**
-   * An empty list of field elements.
-   */
-  static const List<FieldElement> EMPTY_LIST = const <FieldElement>[];
-
-  /**
-   * Return {@code true} if this element is an enum constant.
-   */
-  bool get isEnumConstant;
-
-  /**
-   * Return the resolved [VariableDeclaration] or [EnumConstantDeclaration]
-   * node that declares this [FieldElement].
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  AstNode computeNode();
-}
-
-/**
- * A concrete implementation of a [FieldElement].
- */
-class FieldElementImpl extends PropertyInducingElementImpl
-    with PotentiallyConstVariableElement implements FieldElement {
-  /**
-   * An empty list of field elements.
-   */
-  @deprecated // Use FieldElement.EMPTY_LIST
-  static const List<FieldElement> EMPTY_ARRAY = const <FieldElement>[];
-
-  /**
-   * Initialize a newly created synthetic field element to have the given [name]
-   * at the given [offset].
-   */
-  FieldElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created field element to have the given [name].
-   */
-  FieldElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  ClassElement get enclosingElement => super.enclosingElement as ClassElement;
-
-  @override
-  bool get isEnumConstant =>
-      enclosingElement != null ? enclosingElement.isEnum : false;
-
-  @override
-  bool get isStatic => hasModifier(Modifier.STATIC);
-
-  @override
-  ElementKind get kind => ElementKind.FIELD;
-
-  /**
-   * Set whether this field is static.
-   */
-  void set static(bool isStatic) {
-    setModifier(Modifier.STATIC, isStatic);
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitFieldElement(this);
-
-  @override
-  AstNode computeNode() {
-    if (isEnumConstant) {
-      return getNodeMatching((node) => node is EnumConstantDeclaration);
-    } else {
-      return getNodeMatching((node) => node is VariableDeclaration);
-    }
-  }
-}
-
-/**
- * A field formal parameter defined within a constructor element.
- */
-abstract class FieldFormalParameterElement implements ParameterElement {
-  /**
-   * Return the field element associated with this field formal parameter, or
-   * `null` if the parameter references a field that doesn't exist.
-   */
-  FieldElement get field;
-}
-
-/**
- * A [ParameterElementImpl] that has the additional information of the
- * [FieldElement] associated with the parameter.
- */
-class FieldFormalParameterElementImpl extends ParameterElementImpl
-    implements FieldFormalParameterElement {
-  /**
-   * The field associated with this field formal parameter.
-   */
-  FieldElement field;
-
-  /**
-   * Initialize a newly created parameter element to have the given [name].
-   */
-  FieldFormalParameterElementImpl(Identifier name) : super.forNode(name);
-
-  @override
-  bool get isInitializingFormal => true;
-
-  @override
-  accept(ElementVisitor visitor) =>
-      visitor.visitFieldFormalParameterElement(this);
-}
-
-/**
- * A parameter element defined in a parameterized type where the values of the
- * type parameters are known.
- */
-class FieldFormalParameterMember extends ParameterMember
-    implements FieldFormalParameterElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  FieldFormalParameterMember(
-      FieldFormalParameterElement baseElement, ParameterizedType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  FieldElement get field {
-    FieldElement field = (baseElement as FieldFormalParameterElement).field;
-    if (field is FieldElement) {
-      return FieldMember.from(field, definingType);
-    }
-    return field;
-  }
-
-  @override
-  accept(ElementVisitor visitor) =>
-      visitor.visitFieldFormalParameterElement(this);
-}
-
-/**
- * A field element defined in a parameterized type where the values of the type
- * parameters are known.
- */
-class FieldMember extends VariableMember implements FieldElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  FieldMember(FieldElement baseElement, InterfaceType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  FieldElement get baseElement => super.baseElement as FieldElement;
-
-  @override
-  InterfaceType get definingType => super.definingType as InterfaceType;
-
-  @override
-  ClassElement get enclosingElement => baseElement.enclosingElement;
-
-  @override
-  PropertyAccessorElement get getter =>
-      PropertyAccessorMember.from(baseElement.getter, definingType);
-
-  @override
-  bool get isEnumConstant => baseElement.isEnumConstant;
-
-  @override
-  bool get isStatic => baseElement.isStatic;
-
-  @override
-  DartType get propagatedType => substituteFor(baseElement.propagatedType);
-
-  @override
-  PropertyAccessorElement get setter =>
-      PropertyAccessorMember.from(baseElement.setter, definingType);
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitFieldElement(this);
-
-  @override
-  VariableDeclaration computeNode() => baseElement.computeNode();
-
-  @override
-  String toString() => '$type $displayName';
-
-  /**
-   * If the given [field]'s type is different when any type parameters from the
-   * defining type's declaration are replaced with the actual type arguments
-   * from the [definingType], create a field member representing the given
-   * field. Return the member that was created, or the base field if no member
-   * was created.
-   */
-  static FieldElement from(FieldElement field, InterfaceType definingType) {
-    if (!_isChangedByTypeSubstitution(field, definingType)) {
-      return field;
-    }
-    // TODO(brianwilkerson) Consider caching the substituted type in the
-    // instance. It would use more memory but speed up some operations.
-    // We need to see how often the type is being re-computed.
-    return new FieldMember(field, definingType);
-  }
-
-  /**
-   * Determine whether the given [field]'s type is changed when type parameters
-   * from the [definingType]'s declaration are replaced with the actual type
-   * arguments from the defining type.
-   */
-  static bool _isChangedByTypeSubstitution(
-      FieldElement field, InterfaceType definingType) {
-    List<DartType> argumentTypes = definingType.typeArguments;
-    if (field != null && argumentTypes.length != 0) {
-      DartType baseType = field.type;
-      List<DartType> parameterTypes = definingType.element.type.typeArguments;
-      if (baseType != null) {
-        DartType substitutedType =
-            baseType.substitute2(argumentTypes, parameterTypes);
-        if (baseType != substitutedType) {
-          return true;
-        }
-      }
-      // If the field has a propagated type, then we need to check whether the
-      // propagated type needs substitution.
-      DartType basePropagatedType = field.propagatedType;
-      if (basePropagatedType != null) {
-        DartType substitutedPropagatedType =
-            basePropagatedType.substitute2(argumentTypes, parameterTypes);
-        if (basePropagatedType != substitutedPropagatedType) {
-          return true;
-        }
-      }
-    }
-    return false;
-  }
-}
-
-/**
- * A (non-method) function. This can be either a top-level function, a local
- * function, a closure, or the initialization expression for a field or
- * variable.
- */
-abstract class FunctionElement implements ExecutableElement, LocalElement {
-  /**
-   * An empty list of function elements.
-   */
-  static const List<FunctionElement> EMPTY_LIST = const <FunctionElement>[];
-
-  /**
-   * The name of the method that can be implemented by a class to allow its
-   * instances to be invoked as if they were a function.
-   */
-  static final String CALL_METHOD_NAME = "call";
-
-  /**
-   * The name of the synthetic function defined for libraries that are deferred.
-   */
-  static final String LOAD_LIBRARY_NAME = "loadLibrary";
-
-  /**
-   * The name of the function used as an entry point.
-   */
-  static const String MAIN_FUNCTION_NAME = "main";
-
-  /**
-   * The name of the method that will be invoked if an attempt is made to invoke
-   * an undefined method on an object.
-   */
-  static final String NO_SUCH_METHOD_METHOD_NAME = "noSuchMethod";
-
-  /**
-   * Return `true` if the function is an entry point, i.e. a top-level function
-   * and has the name `main`.
-   */
-  bool get isEntryPoint;
-
-  /**
-   * Return the resolved function declaration node that declares this element.
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  FunctionDeclaration computeNode();
-}
-
-/**
- * A concrete implementation of a [FunctionElement].
- */
-class FunctionElementImpl extends ExecutableElementImpl
-    implements FunctionElement {
-  /**
-   * An empty list of function elements.
-   */
-  @deprecated // Use FunctionElement.EMPTY_LIST
-  static const List<FunctionElement> EMPTY_ARRAY = const <FunctionElement>[];
-
-  /**
-   * The offset to the beginning of the visible range for this element.
-   */
-  int _visibleRangeOffset = 0;
-
-  /**
-   * The length of the visible range for this element, or `-1` if this element
-   * does not have a visible range.
-   */
-  int _visibleRangeLength = -1;
-
-  /**
-   * Initialize a newly created function element to have the given [name] and
-   * [offset].
-   */
-  FunctionElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created function element to have the given [name].
-   */
-  FunctionElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Initialize a newly created function element to have no name and the given
-   * [offset]. This is used for function expressions, that have no name.
-   */
-  FunctionElementImpl.forOffset(int nameOffset) : super("", nameOffset);
-
-  @override
-  String get identifier {
-    String identifier = super.identifier;
-    if (!isStatic) {
-      identifier += "@$nameOffset";
-    }
-    return identifier;
-  }
-
-  @override
-  bool get isEntryPoint {
-    return isStatic && displayName == FunctionElement.MAIN_FUNCTION_NAME;
-  }
-
-  @override
-  bool get isStatic => enclosingElement is CompilationUnitElement;
-
-  @override
-  ElementKind get kind => ElementKind.FUNCTION;
-
-  @override
-  SourceRange get visibleRange {
-    if (_visibleRangeLength < 0) {
-      return null;
-    }
-    return new SourceRange(_visibleRangeOffset, _visibleRangeLength);
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitFunctionElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    String name = displayName;
-    if (name != null) {
-      buffer.write(name);
-    }
-    super.appendTo(buffer);
-  }
-
-  @override
-  FunctionDeclaration computeNode() =>
-      getNodeMatching((node) => node is FunctionDeclaration);
-
-  /**
-   * Set the visible range for this element to the range starting at the given
-   * [offset] with the given [length].
-   */
-  void setVisibleRange(int offset, int length) {
-    _visibleRangeOffset = offset;
-    _visibleRangeLength = length;
-  }
-}
-
-/**
- * The type of a function, method, constructor, getter, or setter. Function
- * types come in three variations:
- *
- * * The types of functions that only have required parameters. These have the
- *   general form <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T</i>.
- * * The types of functions with optional positional parameters. These have the
- *   general form <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, [T<sub>n+1</sub>
- *   &hellip;, T<sub>n+k</sub>]) &rarr; T</i>.
- * * The types of functions with named parameters. These have the general form
- *   <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, {T<sub>x1</sub> x1, &hellip;,
- *   T<sub>xk</sub> xk}) &rarr; T</i>.
- */
-abstract class FunctionType implements ParameterizedType {
-  /**
-   * Return a map from the names of named parameters to the types of the named
-   * parameters of this type of function. The entries in the map will be
-   * iterated in the same order as the order in which the named parameters were
-   * defined. If there were no named parameters declared then the map will be
-   * empty.
-   */
-  Map<String, DartType> get namedParameterTypes;
-
-  /**
-   * Return a list containing the types of the normal parameters of this type of
-   * function. The parameter types are in the same order as they appear in the
-   * declaration of the function.
-   */
-  List<DartType> get normalParameterTypes;
-
-  /**
-   * Return a map from the names of optional (positional) parameters to the
-   * types of the optional parameters of this type of function. The entries in
-   * the map will be iterated in the same order as the order in which the
-   * optional parameters were defined. If there were no optional parameters
-   * declared then the map will be empty.
-   */
-  List<DartType> get optionalParameterTypes;
-
-  /**
-   * Return a list containing the parameters elements of this type of function.
-   * The parameter types are in the same order as they appear in the declaration
-   * of the function.
-   */
-  List<ParameterElement> get parameters;
-
-  /**
-   * Return the type of object returned by this type of function.
-   */
-  DartType get returnType;
-
-  /**
-   * Return `true` if this type is a subtype of the given [type].
-   *
-   * A function type <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T</i> is
-   * a subtype of the function type <i>(S<sub>1</sub>, &hellip;, S<sub>n</sub>)
-   * &rarr; S</i>, if all of the following conditions are met:
-   *
-   * * Either
-   *   * <i>S</i> is void, or
-   *   * <i>T &hArr; S</i>.
-   *
-   * * For all <i>i</i>, 1 <= <i>i</i> <= <i>n</i>, <i>T<sub>i</sub> &hArr;
-   *   S<sub>i</sub></i>.
-   *
-   * A function type <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>,
-   * [T<sub>n+1</sub>, &hellip;, T<sub>n+k</sub>]) &rarr; T</i> is a subtype of
-   * the function type <i>(S<sub>1</sub>, &hellip;, S<sub>n</sub>,
-   * [S<sub>n+1</sub>, &hellip;, S<sub>n+m</sub>]) &rarr; S</i>, if all of the
-   * following conditions are met:
-   *
-   * * Either
-   *   * <i>S</i> is void, or
-   *   * <i>T &hArr; S</i>.
-   *
-   * * <i>k</i> >= <i>m</i> and for all <i>i</i>, 1 <= <i>i</i> <= <i>n+m</i>,
-   *   <i>T<sub>i</sub> &hArr; S<sub>i</sub></i>.
-   *
-   * A function type <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>,
-   * {T<sub>x1</sub> x1, &hellip;, T<sub>xk</sub> xk}) &rarr; T</i> is a subtype
-   * of the function type <i>(S<sub>1</sub>, &hellip;, S<sub>n</sub>,
-   * {S<sub>y1</sub> y1, &hellip;, S<sub>ym</sub> ym}) &rarr; S</i>, if all of
-   * the following conditions are met:
-   * * Either
-   *   * <i>S</i> is void,
-   *   * or <i>T &hArr; S</i>.
-   *
-   * * For all <i>i</i>, 1 <= <i>i</i> <= <i>n</i>, <i>T<sub>i</sub> &hArr;
-   *   S<sub>i</sub></i>.
-   * * <i>k</i> >= <i>m</i> and <i>y<sub>i</sub></i> in <i>{x<sub>1</sub>,
-   *   &hellip;, x<sub>k</sub>}</i>, 1 <= <i>i</i> <= <i>m</i>.
-   * * For all <i>y<sub>i</sub></i> in <i>{y<sub>1</sub>, &hellip;,
-   *   y<sub>m</sub>}</i>, <i>y<sub>i</sub> = x<sub>j</sub> => Tj &hArr; Si</i>.
-   *
-   * In addition, the following subtype rules apply:
-   *
-   * <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, []) &rarr; T <: (T<sub>1</sub>,
-   * &hellip;, T<sub>n</sub>) &rarr; T.</i><br>
-   * <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T <: (T<sub>1</sub>,
-   * &hellip;, T<sub>n</sub>, {}) &rarr; T.</i><br>
-   * <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>, {}) &rarr; T <: (T<sub>1</sub>,
-   * &hellip;, T<sub>n</sub>) &rarr; T.</i><br>
-   * <i>(T<sub>1</sub>, &hellip;, T<sub>n</sub>) &rarr; T <: (T<sub>1</sub>,
-   * &hellip;, T<sub>n</sub>, []) &rarr; T.</i>
-   *
-   * All functions implement the class `Function`. However not all function
-   * types are a subtype of `Function`. If an interface type <i>I</i> includes a
-   * method named `call()`, and the type of `call()` is the function type
-   * <i>F</i>, then <i>I</i> is considered to be a subtype of <i>F</i>.
-   */
-  @override
-  bool isSubtypeOf(DartType type);
-
-  @override
-  FunctionType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes);
-
-  /**
-   * Return the type resulting from substituting the given [argumentTypes] for
-   * this type's parameters. This is fully equivalent to
-   * `substitute(argumentTypes, getTypeArguments())`.
-   */
-  FunctionType substitute3(List<DartType> argumentTypes);
-}
-
-/**
- * A function type alias (`typedef`).
- */
-abstract class FunctionTypeAliasElement implements TypeDefiningElement {
-  /**
-   * An empty array of type alias elements.
-   */
-  static List<FunctionTypeAliasElement> EMPTY_LIST =
-      new List<FunctionTypeAliasElement>(0);
-
-  /**
-   * Return the compilation unit in which this type alias is defined.
-   */
-  @override
-  CompilationUnitElement get enclosingElement;
-
-  /**
-   * Return a list containing all of the parameters defined by this type alias.
-   */
-  List<ParameterElement> get parameters;
-
-  /**
-   * Return the return type defined by this type alias.
-   */
-  DartType get returnType;
-
-  @override
-  FunctionType get type;
-
-  /**
-   * Return a list containing all of the type parameters defined for this type.
-   */
-  List<TypeParameterElement> get typeParameters;
-
-  /**
-   * Return the resolved function type alias node that declares this element.
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  FunctionTypeAlias computeNode();
-}
-
-/**
- * A concrete implementation of a [FunctionTypeAliasElement].
- */
-class FunctionTypeAliasElementImpl extends ElementImpl
-    implements FunctionTypeAliasElement {
-  /**
-   * An empty array of type alias elements.
-   */
-  @deprecated // Use FunctionTypeAliasElement.EMPTY_LIST
-  static List<FunctionTypeAliasElement> EMPTY_ARRAY =
-      new List<FunctionTypeAliasElement>(0);
-
-  /**
-   * A list containing all of the parameters defined by this type alias.
-   */
-  List<ParameterElement> _parameters = ParameterElement.EMPTY_LIST;
-
-  /**
-   * The return type defined by this type alias.
-   */
-  DartType returnType;
-
-  /**
-   * The type of function defined by this type alias.
-   */
-  FunctionType type;
-
-  /**
-   * A list containing all of the type parameters defined for this type.
-   */
-  List<TypeParameterElement> _typeParameters = TypeParameterElement.EMPTY_LIST;
-
-  /**
-   * Initialize a newly created type alias element to have the given name.
-   *
-   * [name] the name of this element
-   * [nameOffset] the offset of the name of this element in the file that
-   *    contains the declaration of this element
-   */
-  FunctionTypeAliasElementImpl(String name, int nameOffset)
-      : super(name, nameOffset);
-
-  /**
-   * Initialize a newly created type alias element to have the given [name].
-   */
-  FunctionTypeAliasElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  CompilationUnitElement get enclosingElement =>
-      super.enclosingElement as CompilationUnitElement;
-
-  @override
-  ElementKind get kind => ElementKind.FUNCTION_TYPE_ALIAS;
-
-  @override
-  List<ParameterElement> get parameters => _parameters;
-
-  /**
-   * Set the parameters defined by this type alias to the given [parameters].
-   */
-  void set parameters(List<ParameterElement> parameters) {
-    if (parameters != null) {
-      for (ParameterElement parameter in parameters) {
-        (parameter as ParameterElementImpl).enclosingElement = this;
-      }
-    }
-    this._parameters = parameters;
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters => _typeParameters;
-
-  /**
-   * Set the type parameters defined for this type to the given
-   * [typeParameters].
-   */
-  void set typeParameters(List<TypeParameterElement> typeParameters) {
-    for (TypeParameterElement typeParameter in typeParameters) {
-      (typeParameter as TypeParameterElementImpl).enclosingElement = this;
-    }
-    this._typeParameters = typeParameters;
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitFunctionTypeAliasElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write("typedef ");
-    buffer.write(displayName);
-    int typeParameterCount = _typeParameters.length;
-    if (typeParameterCount > 0) {
-      buffer.write("<");
-      for (int i = 0; i < typeParameterCount; i++) {
-        if (i > 0) {
-          buffer.write(", ");
-        }
-        (_typeParameters[i] as TypeParameterElementImpl).appendTo(buffer);
-      }
-      buffer.write(">");
-    }
-    buffer.write("(");
-    int parameterCount = _parameters.length;
-    for (int i = 0; i < parameterCount; i++) {
-      if (i > 0) {
-        buffer.write(", ");
-      }
-      (_parameters[i] as ParameterElementImpl).appendTo(buffer);
-    }
-    buffer.write(")");
-    if (type != null) {
-      buffer.write(Element.RIGHT_ARROW);
-      buffer.write(type.returnType);
-    } else if (returnType != null) {
-      buffer.write(Element.RIGHT_ARROW);
-      buffer.write(returnType);
-    }
-  }
-
-  @override
-  FunctionTypeAlias computeNode() =>
-      getNodeMatching((node) => node is FunctionTypeAlias);
-
-  @override
-  ElementImpl getChild(String identifier) {
-    for (VariableElement parameter in _parameters) {
-      if ((parameter as VariableElementImpl).identifier == identifier) {
-        return parameter as VariableElementImpl;
-      }
-    }
-    for (TypeParameterElement typeParameter in _typeParameters) {
-      if ((typeParameter as TypeParameterElementImpl).identifier ==
-          identifier) {
-        return typeParameter as TypeParameterElementImpl;
-      }
-    }
-    return null;
-  }
-
-  /**
-   * Set the parameters defined by this type alias to the given [parameters]
-   * without becoming the parent of the parameters. This should only be used by
-   * the [TypeResolverVisitor] when creating a synthetic type alias.
-   */
-  void shareParameters(List<ParameterElement> parameters) {
-    this._parameters = parameters;
-  }
-
-  /**
-   * Set the type parameters defined for this type to the given [typeParameters]
-   * without becoming the parent of the parameters. This should only be used by
-   * the [TypeResolverVisitor] when creating a synthetic type alias.
-   */
-  void shareTypeParameters(List<TypeParameterElement> typeParameters) {
-    this._typeParameters = typeParameters;
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(_parameters, visitor);
-    safelyVisitChildren(_typeParameters, visitor);
-  }
-}
-
-/**
- * The type of a function, method, constructor, getter, or setter.
- */
-class FunctionTypeImpl extends TypeImpl implements FunctionType {
-  /**
-   * A list containing the actual types of the type arguments.
-   */
-  List<DartType> typeArguments = DartType.EMPTY_LIST;
-
-  /**
-   * The set of typedefs which should not be expanded when exploring this type,
-   * to avoid creating infinite types in response to self-referential typedefs.
-   */
-  final List<FunctionTypeAliasElement> prunedTypedefs;
-
-  /**
-   * Initialize a newly created function type to be declared by the given
-   * [element].
-   */
-  FunctionTypeImpl(ExecutableElement element, [this.prunedTypedefs])
-      : super(element, null);
-
-  /**
-   * Initialize a newly created function type to be declared by the given
-   * [element].
-   */
-  @deprecated // Use new FunctionTypeImpl(element)
-  FunctionTypeImpl.con1(ExecutableElement element)
-      : prunedTypedefs = null,
-        super(element, null);
-
-  /**
-   * Initialize a newly created function type to be declared by the given
-   * [element].
-   */
-  @deprecated // Use new FunctionTypeImpl.forTypedef(element)
-  FunctionTypeImpl.con2(FunctionTypeAliasElement element)
-      : prunedTypedefs = null,
-        super(element, element == null ? null : element.name);
-
-  /**
-   * Initialize a newly created function type to be declared by the given
-   * [element].
-   */
-  FunctionTypeImpl.forTypedef(FunctionTypeAliasElement element,
-      [this.prunedTypedefs])
-      : super(element, element == null ? null : element.name);
-
-  /**
-   * Private constructor.
-   */
-  FunctionTypeImpl._(Element element, String name, this.prunedTypedefs)
-      : super(element, name);
-
-  /**
-   * Return the base parameter elements of this function element.
-   */
-  List<ParameterElement> get baseParameters {
-    Element element = this.element;
-    if (element is ExecutableElement) {
-      return element.parameters;
-    } else {
-      return (element as FunctionTypeAliasElement).parameters;
-    }
-  }
-
-  /**
-   * Return the return type defined by this function's element.
-   */
-  DartType get baseReturnType {
-    Element element = this.element;
-    if (element is ExecutableElement) {
-      return element.returnType;
-    } else {
-      return (element as FunctionTypeAliasElement).returnType;
-    }
-  }
-
-  @override
-  String get displayName {
-    String name = this.name;
-    if (name == null || name.length == 0) {
-      // Function types have an empty name when they are defined implicitly by
-      // either a closure or as part of a parameter declaration.
-      List<DartType> normalParameterTypes = this.normalParameterTypes;
-      List<DartType> optionalParameterTypes = this.optionalParameterTypes;
-      Map<String, DartType> namedParameterTypes = this.namedParameterTypes;
-      DartType returnType = this.returnType;
-      StringBuffer buffer = new StringBuffer();
-      buffer.write("(");
-      bool needsComma = false;
-      if (normalParameterTypes.length > 0) {
-        for (DartType type in normalParameterTypes) {
-          if (needsComma) {
-            buffer.write(", ");
-          } else {
-            needsComma = true;
-          }
-          buffer.write(type.displayName);
-        }
-      }
-      if (optionalParameterTypes.length > 0) {
-        if (needsComma) {
-          buffer.write(", ");
-          needsComma = false;
-        }
-        buffer.write("[");
-        for (DartType type in optionalParameterTypes) {
-          if (needsComma) {
-            buffer.write(", ");
-          } else {
-            needsComma = true;
-          }
-          buffer.write(type.displayName);
-        }
-        buffer.write("]");
-        needsComma = true;
-      }
-      if (namedParameterTypes.length > 0) {
-        if (needsComma) {
-          buffer.write(", ");
-          needsComma = false;
-        }
-        buffer.write("{");
-        namedParameterTypes.forEach((String name, DartType type) {
-          if (needsComma) {
-            buffer.write(", ");
-          } else {
-            needsComma = true;
-          }
-          buffer.write(name);
-          buffer.write(": ");
-          buffer.write(type.displayName);
-        });
-        buffer.write("}");
-        needsComma = true;
-      }
-      buffer.write(")");
-      buffer.write(Element.RIGHT_ARROW);
-      if (returnType == null) {
-        buffer.write("null");
-      } else {
-        buffer.write(returnType.displayName);
-      }
-      name = buffer.toString();
-    }
-    return name;
-  }
-
-  @override
-  int get hashCode {
-    if (element == null) {
-      return 0;
-    }
-    // Reference the arrays of parameters
-    List<DartType> normalParameterTypes = this.normalParameterTypes;
-    List<DartType> optionalParameterTypes = this.optionalParameterTypes;
-    Iterable<DartType> namedParameterTypes = this.namedParameterTypes.values;
-    // Generate the hashCode
-    int code = (returnType as TypeImpl).hashCode;
-    for (int i = 0; i < normalParameterTypes.length; i++) {
-      code = (code << 1) + (normalParameterTypes[i] as TypeImpl).hashCode;
-    }
-    for (int i = 0; i < optionalParameterTypes.length; i++) {
-      code = (code << 1) + (optionalParameterTypes[i] as TypeImpl).hashCode;
-    }
-    for (DartType type in namedParameterTypes) {
-      code = (code << 1) + (type as TypeImpl).hashCode;
-    }
-    return code;
-  }
-
-  @override
-  Map<String, DartType> get namedParameterTypes {
-    LinkedHashMap<String, DartType> namedParameterTypes =
-        new LinkedHashMap<String, DartType>();
-    List<ParameterElement> parameters = baseParameters;
-    if (parameters.length == 0) {
-      return namedParameterTypes;
-    }
-    List<DartType> typeParameters =
-        TypeParameterTypeImpl.getTypes(this.typeParameters);
-    for (ParameterElement parameter in parameters) {
-      if (parameter.parameterKind == ParameterKind.NAMED) {
-        DartType type = parameter.type;
-        if (typeArguments.length != 0 &&
-            typeArguments.length == typeParameters.length) {
-          type = (type as TypeImpl).substitute2(
-              typeArguments, typeParameters, newPrune);
-        } else {
-          type = (type as TypeImpl).pruned(newPrune);
-        }
-        namedParameterTypes[parameter.name] = type;
-      }
-    }
-    return namedParameterTypes;
-  }
-
-  /**
-   * Determine the new set of typedefs which should be pruned when expanding
-   * this function type.
-   */
-  List<FunctionTypeAliasElement> get newPrune {
-    Element element = this.element;
-    if (element is FunctionTypeAliasElement && !element.isSynthetic) {
-      // This typedef should be pruned, along with anything that was previously
-      // pruned.
-      if (prunedTypedefs == null) {
-        return <FunctionTypeAliasElement>[element];
-      } else {
-        return new List<FunctionTypeAliasElement>.from(prunedTypedefs)
-          ..add(element);
-      }
-    } else {
-      // This is not a typedef, so nothing additional needs to be pruned.
-      return prunedTypedefs;
-    }
-  }
-
-  @override
-  List<DartType> get normalParameterTypes {
-    List<ParameterElement> parameters = baseParameters;
-    if (parameters.length == 0) {
-      return DartType.EMPTY_LIST;
-    }
-    List<DartType> typeParameters =
-        TypeParameterTypeImpl.getTypes(this.typeParameters);
-    List<DartType> types = new List<DartType>();
-    for (ParameterElement parameter in parameters) {
-      if (parameter.parameterKind == ParameterKind.REQUIRED) {
-        DartType type = parameter.type;
-        if (typeArguments.length != 0 &&
-            typeArguments.length == typeParameters.length) {
-          type = (type as TypeImpl).substitute2(
-              typeArguments, typeParameters, newPrune);
-        } else {
-          type = (type as TypeImpl).pruned(newPrune);
-        }
-        types.add(type);
-      }
-    }
-    return types;
-  }
-
-  @override
-  List<DartType> get optionalParameterTypes {
-    List<ParameterElement> parameters = baseParameters;
-    if (parameters.length == 0) {
-      return DartType.EMPTY_LIST;
-    }
-    List<DartType> typeParameters =
-        TypeParameterTypeImpl.getTypes(this.typeParameters);
-    List<DartType> types = new List<DartType>();
-    for (ParameterElement parameter in parameters) {
-      if (parameter.parameterKind == ParameterKind.POSITIONAL) {
-        DartType type = parameter.type;
-        if (typeArguments.length != 0 &&
-            typeArguments.length == typeParameters.length) {
-          type = (type as TypeImpl).substitute2(
-              typeArguments, typeParameters, newPrune);
-        } else {
-          type = (type as TypeImpl).pruned(newPrune);
-        }
-        types.add(type);
-      }
-    }
-    return types;
-  }
-
-  @override
-  List<ParameterElement> get parameters {
-    List<ParameterElement> baseParameters = this.baseParameters;
-    // no parameters, quick return
-    int parameterCount = baseParameters.length;
-    if (parameterCount == 0) {
-      return baseParameters;
-    }
-    // create specialized parameters
-    List<ParameterElement> specializedParameters =
-        new List<ParameterElement>(parameterCount);
-    for (int i = 0; i < parameterCount; i++) {
-      specializedParameters[i] = ParameterMember.from(baseParameters[i], this);
-    }
-    return specializedParameters;
-  }
-
-  @override
-  DartType get returnType {
-    DartType baseReturnType = this.baseReturnType;
-    if (baseReturnType == null) {
-      // TODO(brianwilkerson) This is a patch. The return type should never be
-      // null and we need to understand why it is and fix it.
-      return DynamicTypeImpl.instance;
-    }
-    // If there are no arguments to substitute, or if the arguments size doesn't
-    // match the parameter size, return the base return type.
-    if (typeArguments.length == 0 ||
-        typeArguments.length != typeParameters.length) {
-      return (baseReturnType as TypeImpl).pruned(newPrune);
-    }
-    return (baseReturnType as TypeImpl).substitute2(typeArguments,
-        TypeParameterTypeImpl.getTypes(typeParameters), newPrune);
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters {
-    Element element = this.element;
-    if (element is FunctionTypeAliasElement) {
-      return element.typeParameters;
-    }
-    ClassElement definingClass =
-        element.getAncestor((element) => element is ClassElement);
-    if (definingClass != null) {
-      return definingClass.typeParameters;
-    }
-    return TypeParameterElement.EMPTY_LIST;
-  }
-
-  @override
-  bool operator ==(Object object) {
-    if (object is! FunctionTypeImpl) {
-      return false;
-    }
-    FunctionTypeImpl otherType = object as FunctionTypeImpl;
-    return returnType == otherType.returnType &&
-        TypeImpl.equalArrays(
-            normalParameterTypes, otherType.normalParameterTypes) &&
-        TypeImpl.equalArrays(
-            optionalParameterTypes, otherType.optionalParameterTypes) &&
-        _equals(namedParameterTypes, otherType.namedParameterTypes);
-  }
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    List<DartType> normalParameterTypes = this.normalParameterTypes;
-    List<DartType> optionalParameterTypes = this.optionalParameterTypes;
-    Map<String, DartType> namedParameterTypes = this.namedParameterTypes;
-    DartType returnType = this.returnType;
-    buffer.write("(");
-    bool needsComma = false;
-    if (normalParameterTypes.length > 0) {
-      for (DartType type in normalParameterTypes) {
-        if (needsComma) {
-          buffer.write(", ");
-        } else {
-          needsComma = true;
-        }
-        (type as TypeImpl).appendTo(buffer);
-      }
-    }
-    if (optionalParameterTypes.length > 0) {
-      if (needsComma) {
-        buffer.write(", ");
-        needsComma = false;
-      }
-      buffer.write("[");
-      for (DartType type in optionalParameterTypes) {
-        if (needsComma) {
-          buffer.write(", ");
-        } else {
-          needsComma = true;
-        }
-        (type as TypeImpl).appendTo(buffer);
-      }
-      buffer.write("]");
-      needsComma = true;
-    }
-    if (namedParameterTypes.length > 0) {
-      if (needsComma) {
-        buffer.write(", ");
-        needsComma = false;
-      }
-      buffer.write("{");
-      namedParameterTypes.forEach((String name, DartType type) {
-        if (needsComma) {
-          buffer.write(", ");
-        } else {
-          needsComma = true;
-        }
-        buffer.write(name);
-        buffer.write(": ");
-        (type as TypeImpl).appendTo(buffer);
-      });
-      buffer.write("}");
-      needsComma = true;
-    }
-    buffer.write(")");
-    buffer.write(Element.RIGHT_ARROW);
-    if (returnType == null) {
-      buffer.write("null");
-    } else {
-      (returnType as TypeImpl).appendTo(buffer);
-    }
-  }
-
-  @override
-  bool isAssignableTo(DartType type) {
-    // A function type T may be assigned to a function type S, written T <=> S,
-    // iff T <: S.
-    return isSubtypeOf(type);
-  }
-
-  @override
-  bool isMoreSpecificThan(DartType type,
-      [bool withDynamic = false, Set<Element> visitedElements]) {
-    // Note: visitedElements is only used for breaking recursion in the type
-    // hierarchy; we don't use it when recursing into the function type.
-
-    // trivial base cases
-    if (type == null) {
-      return false;
-    } else if (identical(this, type) ||
-        type.isDynamic ||
-        type.isDartCoreFunction ||
-        type.isObject) {
-      return true;
-    } else if (type is! FunctionType) {
-      return false;
-    } else if (this == type) {
-      return true;
-    }
-    FunctionType t = this;
-    FunctionType s = type as FunctionType;
-    List<DartType> tTypes = t.normalParameterTypes;
-    List<DartType> tOpTypes = t.optionalParameterTypes;
-    List<DartType> sTypes = s.normalParameterTypes;
-    List<DartType> sOpTypes = s.optionalParameterTypes;
-    // If one function has positional and the other has named parameters,
-    // return false.
-    if ((sOpTypes.length > 0 && t.namedParameterTypes.length > 0) ||
-        (tOpTypes.length > 0 && s.namedParameterTypes.length > 0)) {
-      return false;
-    }
-    // named parameters case
-    if (t.namedParameterTypes.length > 0) {
-      // check that the number of required parameters are equal, and check that
-      // every t_i is more specific than every s_i
-      if (t.normalParameterTypes.length != s.normalParameterTypes.length) {
-        return false;
-      } else if (t.normalParameterTypes.length > 0) {
-        for (int i = 0; i < tTypes.length; i++) {
-          if (!(tTypes[i] as TypeImpl).isMoreSpecificThan(
-              sTypes[i], withDynamic)) {
-            return false;
-          }
-        }
-      }
-      Map<String, DartType> namedTypesT = t.namedParameterTypes;
-      Map<String, DartType> namedTypesS = s.namedParameterTypes;
-      // if k >= m is false, return false: the passed function type has more
-      // named parameter types than this
-      if (namedTypesT.length < namedTypesS.length) {
-        return false;
-      }
-      // Loop through each element in S verifying that T has a matching
-      // parameter name and that the corresponding type is more specific then
-      // the type in S.
-      for (String keyS in namedTypesS.keys) {
-        DartType typeT = namedTypesT[keyS];
-        if (typeT == null) {
-          return false;
-        }
-        if (!(typeT as TypeImpl).isMoreSpecificThan(
-            namedTypesS[keyS], withDynamic)) {
-          return false;
-        }
-      }
-    } else if (s.namedParameterTypes.length > 0) {
-      return false;
-    } else {
-      // positional parameter case
-      int tArgLength = tTypes.length + tOpTypes.length;
-      int sArgLength = sTypes.length + sOpTypes.length;
-      // Check that the total number of parameters in t is greater than or equal
-      // to the number of parameters in s and that the number of required
-      // parameters in s is greater than or equal to the number of required
-      // parameters in t.
-      if (tArgLength < sArgLength || sTypes.length < tTypes.length) {
-        return false;
-      }
-      if (tOpTypes.length == 0 && sOpTypes.length == 0) {
-        // No positional arguments, don't copy contents to new array
-        for (int i = 0; i < sTypes.length; i++) {
-          if (!(tTypes[i] as TypeImpl).isMoreSpecificThan(
-              sTypes[i], withDynamic)) {
-            return false;
-          }
-        }
-      } else {
-        // Else, we do have positional parameters, copy required and positional
-        // parameter types into arrays to do the compare (for loop below).
-        List<DartType> tAllTypes = new List<DartType>(sArgLength);
-        for (int i = 0; i < tTypes.length; i++) {
-          tAllTypes[i] = tTypes[i];
-        }
-        for (int i = tTypes.length, j = 0; i < sArgLength; i++, j++) {
-          tAllTypes[i] = tOpTypes[j];
-        }
-        List<DartType> sAllTypes = new List<DartType>(sArgLength);
-        for (int i = 0; i < sTypes.length; i++) {
-          sAllTypes[i] = sTypes[i];
-        }
-        for (int i = sTypes.length, j = 0; i < sArgLength; i++, j++) {
-          sAllTypes[i] = sOpTypes[j];
-        }
-        for (int i = 0; i < sAllTypes.length; i++) {
-          if (!(tAllTypes[i] as TypeImpl).isMoreSpecificThan(
-              sAllTypes[i], withDynamic)) {
-            return false;
-          }
-        }
-      }
-    }
-    DartType tRetType = t.returnType;
-    DartType sRetType = s.returnType;
-    return sRetType.isVoid ||
-        (tRetType as TypeImpl).isMoreSpecificThan(sRetType, withDynamic);
-  }
-
-  @override
-  bool isSubtypeOf(DartType type) {
-    // trivial base cases
-    if (type == null) {
-      return false;
-    } else if (identical(this, type) ||
-        type.isDynamic ||
-        type.isDartCoreFunction ||
-        type.isObject) {
-      return true;
-    } else if (type is! FunctionType) {
-      return false;
-    } else if (this == type) {
-      return true;
-    }
-    FunctionType t = this;
-    FunctionType s = type as FunctionType;
-    List<DartType> tTypes = t.normalParameterTypes;
-    List<DartType> tOpTypes = t.optionalParameterTypes;
-    List<DartType> sTypes = s.normalParameterTypes;
-    List<DartType> sOpTypes = s.optionalParameterTypes;
-    // If one function has positional and the other has named parameters,
-    // return false.
-    if ((sOpTypes.length > 0 && t.namedParameterTypes.length > 0) ||
-        (tOpTypes.length > 0 && s.namedParameterTypes.length > 0)) {
-      return false;
-    }
-    // named parameters case
-    if (t.namedParameterTypes.length > 0) {
-      // check that the number of required parameters are equal,
-      // and check that every t_i is assignable to every s_i
-      if (t.normalParameterTypes.length != s.normalParameterTypes.length) {
-        return false;
-      } else if (t.normalParameterTypes.length > 0) {
-        for (int i = 0; i < tTypes.length; i++) {
-          if (!(tTypes[i] as TypeImpl).isAssignableTo(sTypes[i])) {
-            return false;
-          }
-        }
-      }
-      Map<String, DartType> namedTypesT = t.namedParameterTypes;
-      Map<String, DartType> namedTypesS = s.namedParameterTypes;
-      // if k >= m is false, return false: the passed function type has more
-      // named parameter types than this
-      if (namedTypesT.length < namedTypesS.length) {
-        return false;
-      }
-      // Loop through each element in S verifying that T has a matching
-      // parameter name and that the corresponding type is assignable to the
-      // type in S.
-      for (String keyS in namedTypesS.keys) {
-        DartType typeT = namedTypesT[keyS];
-        if (typeT == null) {
-          return false;
-        }
-        if (!(typeT as TypeImpl).isAssignableTo(namedTypesS[keyS])) {
-          return false;
-        }
-      }
-    } else if (s.namedParameterTypes.length > 0) {
-      return false;
-    } else {
-      // positional parameter case
-      int tArgLength = tTypes.length + tOpTypes.length;
-      int sArgLength = sTypes.length + sOpTypes.length;
-      // Check that the total number of parameters in t is greater than or
-      // equal to the number of parameters in s and that the number of
-      // required parameters in s is greater than or equal to the number of
-      // required parameters in t.
-      if (tArgLength < sArgLength || sTypes.length < tTypes.length) {
-        return false;
-      }
-      if (tOpTypes.length == 0 && sOpTypes.length == 0) {
-        // No positional arguments, don't copy contents to new array
-        for (int i = 0; i < sTypes.length; i++) {
-          if (!(tTypes[i] as TypeImpl).isAssignableTo(sTypes[i])) {
-            return false;
-          }
-        }
-      } else {
-        // Else, we do have positional parameters, copy required and
-        // positional parameter types into arrays to do the compare (for loop
-        // below).
-        List<DartType> tAllTypes = new List<DartType>(sArgLength);
-        for (int i = 0; i < tTypes.length; i++) {
-          tAllTypes[i] = tTypes[i];
-        }
-        for (int i = tTypes.length, j = 0; i < sArgLength; i++, j++) {
-          tAllTypes[i] = tOpTypes[j];
-        }
-        List<DartType> sAllTypes = new List<DartType>(sArgLength);
-        for (int i = 0; i < sTypes.length; i++) {
-          sAllTypes[i] = sTypes[i];
-        }
-        for (int i = sTypes.length, j = 0; i < sArgLength; i++, j++) {
-          sAllTypes[i] = sOpTypes[j];
-        }
-        for (int i = 0; i < sAllTypes.length; i++) {
-          if (!(tAllTypes[i] as TypeImpl).isAssignableTo(sAllTypes[i])) {
-            return false;
-          }
-        }
-      }
-    }
-    DartType tRetType = t.returnType;
-    DartType sRetType = s.returnType;
-    return sRetType.isVoid || (tRetType as TypeImpl).isAssignableTo(sRetType);
-  }
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) {
-    if (prune == null) {
-      return this;
-    } else if (prune.contains(element)) {
-      // Circularity found.  Prune the type declaration.
-      return new CircularTypeImpl();
-    } else {
-      // There should never be a reason to prune a type that has already been
-      // pruned, since pruning is only done when expanding a function type
-      // alias, and function type aliases are always expanded by starting with
-      // base types.
-      assert(this.prunedTypedefs == null);
-      FunctionTypeImpl result = new FunctionTypeImpl._(element, name, prune);
-      result.typeArguments =
-          typeArguments.map((TypeImpl t) => t.pruned(prune)).toList();
-      return result;
-    }
-  }
-
-  @override
-  DartType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) {
-    // Pruned types should only ever result from peforming type variable
-    // substitution, and it doesn't make sense to substitute again after
-    // substituting once.
-    assert(this.prunedTypedefs == null);
-    if (argumentTypes.length != parameterTypes.length) {
-      throw new IllegalArgumentException(
-          "argumentTypes.length (${argumentTypes.length}) != parameterTypes.length (${parameterTypes.length})");
-    }
-    Element element = this.element;
-    if (prune != null && prune.contains(element)) {
-      // Circularity found.  Prune the type declaration.
-      return new CircularTypeImpl();
-    }
-    if (argumentTypes.length == 0) {
-      return this.pruned(prune);
-    }
-    FunctionTypeImpl newType = (element is ExecutableElement)
-        ? new FunctionTypeImpl(element, prune)
-        : new FunctionTypeImpl.forTypedef(
-            element as FunctionTypeAliasElement, prune);
-    newType.typeArguments =
-        TypeImpl.substitute(typeArguments, argumentTypes, parameterTypes);
-    return newType;
-  }
-
-  @override
-  FunctionTypeImpl substitute3(List<DartType> argumentTypes) =>
-      substitute2(argumentTypes, typeArguments);
-
-  /**
-   * Compute the least upper bound of types [f] and [g], both of which are
-   * known to be function types.
-   *
-   * In the event that f and g have different numbers of required parameters,
-   * `null` is returned, in which case the least upper bound is the interface
-   * type `Function`.
-   */
-  static FunctionType computeLeastUpperBound(FunctionType f, FunctionType g) {
-    // TODO(paulberry): implement this.
-    return null;
-  }
-
-  /**
-   * Return `true` if all of the name/type pairs in the first map ([firstTypes])
-   * are equal to the corresponding name/type pairs in the second map
-   * ([secondTypes]). The maps are expected to iterate over their entries in the
-   * same order in which those entries were added to the map.
-   */
-  static bool _equals(
-      Map<String, DartType> firstTypes, Map<String, DartType> secondTypes) {
-    if (secondTypes.length != firstTypes.length) {
-      return false;
-    }
-    Iterator<String> firstKeys = firstTypes.keys.iterator;
-    Iterator<String> secondKeys = secondTypes.keys.iterator;
-    while (firstKeys.moveNext() && secondKeys.moveNext()) {
-      String firstKey = firstKeys.current;
-      String secondKey = secondKeys.current;
-      TypeImpl firstType = firstTypes[firstKey];
-      TypeImpl secondType = secondTypes[secondKey];
-      if (firstKey != secondKey || firstType != secondType) {
-        return false;
-      }
-    }
-    return true;
-  }
-}
-
-/**
- * An element visitor that will recursively visit all of the elements in an
- * element model (like instances of the class [RecursiveElementVisitor]). In
- * addition, when an element of a specific type is visited not only will the
- * visit method for that specific type of element be invoked, but additional
- * methods for the supertypes of that element will also be invoked. For example,
- * using an instance of this class to visit a [MethodElement] will cause the
- * method [visitMethodElement] to be invoked but will also cause the methods
- * [visitExecutableElement] and [visitElement] to be subsequently invoked. This
- * allows visitors to be written that visit all executable elements without
- * needing to override the visit method for each of the specific subclasses of
- * [ExecutableElement].
- *
- * Note, however, that unlike many visitors, element visitors visit objects
- * based on the interfaces implemented by those elements. Because interfaces
- * form a graph structure rather than a tree structure the way classes do, and
- * because it is generally undesirable for an object to be visited more than
- * once, this class flattens the interface graph into a pseudo-tree. In
- * particular, this class treats elements as if the element types were
- * structured in the following way:
- *
- * <pre>
- * Element
- *   ClassElement
- *   CompilationUnitElement
- *   ExecutableElement
- *       ConstructorElement
- *       LocalElement
- *           FunctionElement
- *       MethodElement
- *       PropertyAccessorElement
- *   ExportElement
- *   HtmlElement
- *   ImportElement
- *   LabelElement
- *   LibraryElement
- *   MultiplyDefinedElement
- *   PrefixElement
- *   TypeAliasElement
- *   TypeParameterElement
- *   UndefinedElement
- *   VariableElement
- *       PropertyInducingElement
- *           FieldElement
- *           TopLevelVariableElement
- *       LocalElement
- *           LocalVariableElement
- *           ParameterElement
- *               FieldFormalParameterElement
- * </pre>
- *
- * Subclasses that override a visit method must either invoke the overridden
- * visit method or explicitly invoke the more general visit method. Failure to
- * do so will cause the visit methods for superclasses of the element to not be
- * invoked and will cause the children of the visited node to not be visited.
- */
-class GeneralizingElementVisitor<R> implements ElementVisitor<R> {
-  @override
-  R visitClassElement(ClassElement element) => visitElement(element);
-
-  @override
-  R visitCompilationUnitElement(CompilationUnitElement element) =>
-      visitElement(element);
-
-  @override
-  R visitConstructorElement(ConstructorElement element) =>
-      visitExecutableElement(element);
-
-  R visitElement(Element element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  @deprecated
-  R visitEmbeddedHtmlScriptElement(EmbeddedHtmlScriptElement element) =>
-      visitHtmlScriptElement(element);
-
-  R visitExecutableElement(ExecutableElement element) => visitElement(element);
-
-  @override
-  R visitExportElement(ExportElement element) => visitElement(element);
-
-  @override
-  @deprecated
-  R visitExternalHtmlScriptElement(ExternalHtmlScriptElement element) =>
-      visitHtmlScriptElement(element);
-
-  @override
-  R visitFieldElement(FieldElement element) =>
-      visitPropertyInducingElement(element);
-
-  @override
-  R visitFieldFormalParameterElement(FieldFormalParameterElement element) =>
-      visitParameterElement(element);
-
-  @override
-  R visitFunctionElement(FunctionElement element) => visitLocalElement(element);
-
-  @override
-  R visitFunctionTypeAliasElement(FunctionTypeAliasElement element) =>
-      visitElement(element);
-
-  @override
-  @deprecated
-  R visitHtmlElement(HtmlElement element) => visitElement(element);
-
-  @deprecated
-  R visitHtmlScriptElement(HtmlScriptElement element) => visitElement(element);
-
-  @override
-  R visitImportElement(ImportElement element) => visitElement(element);
-
-  @override
-  R visitLabelElement(LabelElement element) => visitElement(element);
-
-  @override
-  R visitLibraryElement(LibraryElement element) => visitElement(element);
-
-  R visitLocalElement(LocalElement element) {
-    if (element is LocalVariableElement) {
-      return visitVariableElement(element);
-    } else if (element is ParameterElement) {
-      return visitVariableElement(element);
-    } else if (element is FunctionElement) {
-      return visitExecutableElement(element);
-    }
-    return null;
-  }
-
-  @override
-  R visitLocalVariableElement(LocalVariableElement element) =>
-      visitLocalElement(element);
-
-  @override
-  R visitMethodElement(MethodElement element) =>
-      visitExecutableElement(element);
-
-  @override
-  R visitMultiplyDefinedElement(MultiplyDefinedElement element) =>
-      visitElement(element);
-
-  @override
-  R visitParameterElement(ParameterElement element) =>
-      visitLocalElement(element);
-
-  @override
-  R visitPrefixElement(PrefixElement element) => visitElement(element);
-
-  @override
-  R visitPropertyAccessorElement(PropertyAccessorElement element) =>
-      visitExecutableElement(element);
-
-  R visitPropertyInducingElement(PropertyInducingElement element) =>
-      visitVariableElement(element);
-
-  @override
-  R visitTopLevelVariableElement(TopLevelVariableElement element) =>
-      visitPropertyInducingElement(element);
-
-  @override
-  R visitTypeParameterElement(TypeParameterElement element) =>
-      visitElement(element);
-
-  R visitVariableElement(VariableElement element) => visitElement(element);
-}
-
-/**
- * A combinator that causes some of the names in a namespace to be hidden when
- * being imported.
- */
-abstract class HideElementCombinator implements NamespaceCombinator {
-  /**
-   * Return a list containing the names that are not to be made visible in the
-   * importing library even if they are defined in the imported library.
-   */
-  List<String> get hiddenNames;
-}
-
-/**
- * A concrete implementation of a [HideElementCombinator].
- */
-class HideElementCombinatorImpl implements HideElementCombinator {
-  /**
-   * The names that are not to be made visible in the importing library even if
-   * they are defined in the imported library.
-   */
-  List<String> hiddenNames = StringUtilities.EMPTY_ARRAY;
-
-  @override
-  String toString() {
-    StringBuffer buffer = new StringBuffer();
-    buffer.write("show ");
-    int count = hiddenNames.length;
-    for (int i = 0; i < count; i++) {
-      if (i > 0) {
-        buffer.write(", ");
-      }
-      buffer.write(hiddenNames[i]);
-    }
-    return buffer.toString();
-  }
-}
-
-/**
- * An HTML file.
- */
-@deprecated
-abstract class HtmlElement implements Element {
-  /**
-   * An empty list of HTML file elements.
-   */
-  static const List<HtmlElement> EMPTY_LIST = const <HtmlElement>[];
-
-  /**
-   * Return a list containing all of the script elements contained in the HTML
-   * file. This includes scripts with libraries that are defined by the content
-   * of a script tag as well as libraries that are referenced in the `source`
-   * attribute of a script tag.
-   */
-  List<HtmlScriptElement> get scripts;
-}
-
-/**
- * A concrete implementation of an [HtmlElement].
- */
-@deprecated
-class HtmlElementImpl extends ElementImpl implements HtmlElement {
-  /**
-   * An empty list of HTML file elements.
-   */
-  @deprecated // Use HtmlElement.EMPTY_LIST
-  static const List<HtmlElement> EMPTY_ARRAY = const <HtmlElement>[];
-
-  /**
-   * The analysis context in which this library is defined.
-   */
-  final AnalysisContext context;
-
-  /**
-   * The scripts contained in or referenced from script tags in the HTML file.
-   */
-  List<HtmlScriptElement> _scripts = HtmlScriptElement.EMPTY_LIST;
-
-  /**
-   * The source that corresponds to this HTML file.
-   */
-  Source source;
-
-  /**
-   * Initialize a newly created HTML element in the given [context] to have the
-   * given [name].
-   */
-  HtmlElementImpl(this.context, String name) : super(name, -1);
-
-  @override
-  int get hashCode => source.hashCode;
-
-  @override
-  String get identifier => source.encoding;
-
-  @override
-  ElementKind get kind => ElementKind.HTML;
-
-  @override
-  List<HtmlScriptElement> get scripts => _scripts;
-
-  /**
-   * Set the scripts contained in the HTML file to the given [scripts].
-   */
-  void set scripts(List<HtmlScriptElement> scripts) {
-    if (scripts.length == 0) {
-      this._scripts = HtmlScriptElement.EMPTY_LIST;
-      return;
-    }
-    for (HtmlScriptElement script in scripts) {
-      (script as HtmlScriptElementImpl).enclosingElement = this;
-    }
-    this._scripts = scripts;
-  }
-
-  @override
-  bool operator ==(Object object) {
-    if (identical(object, this)) {
-      return true;
-    }
-    return object is HtmlElementImpl && source == object.source;
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitHtmlElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    if (source == null) {
-      buffer.write("{HTML file}");
-    } else {
-      buffer.write(source.fullName);
-    }
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(_scripts, visitor);
-  }
-}
-
-/**
- * A script tag in an HTML file.
- *
- * See [EmbeddedHtmlScriptElement], and [ExternalHtmlScriptElement].
- */
-@deprecated
-abstract class HtmlScriptElement implements Element {
-  /**
-   * An empty list of HTML script elements.
-   */
-  static const List<HtmlScriptElement> EMPTY_LIST = const <HtmlScriptElement>[];
-}
-
-/**
- * A concrete implementation of an [HtmlScriptElement].
- */
-@deprecated
-abstract class HtmlScriptElementImpl extends ElementImpl
-    implements HtmlScriptElement {
-  /**
-   * An empty list of HTML script elements.
-   */
-  @deprecated // Use HtmlScriptElement.EMPTY_LIST
-  static const List<HtmlScriptElement> EMPTY_ARRAY =
-      const <HtmlScriptElement>[];
-
-  /**
-   * Initialize a newly created script element corresponding to the given
-   * [node].
-   */
-  HtmlScriptElementImpl(XmlTagNode node)
-      : super(node.tag, node.tagToken.offset);
-}
-
-/**
- * A single import directive within a library.
- */
-abstract class ImportElement implements Element, UriReferencedElement {
-  /**
-   * An empty list of import elements.
-   */
-  @deprecated // Use ImportElement.EMPTY_LIST
-  static const List<ImportElement> EMPTY_ARRAY = const <ImportElement>[];
-
-  /**
-   * An empty list of import elements.
-   */
-  static const List<ImportElement> EMPTY_LIST = const <ImportElement>[];
-
-  /**
-   * Return a list containing the combinators that were specified as part of the
-   * import directive in the order in which they were specified.
-   */
-  List<NamespaceCombinator> get combinators;
-
-  /**
-   * Return the library that is imported into this library by this import
-   * directive.
-   */
-  LibraryElement get importedLibrary;
-
-  /**
-   * Return `true` if this import is for a deferred library.
-   */
-  bool get isDeferred;
-
-  /**
-   * Return the prefix that was specified as part of the import directive, or
-   * `null` if there was no prefix specified.
-   */
-  PrefixElement get prefix;
-
-  /**
-   * Return the offset of the prefix of this import in the file that contains
-   * this import directive, or `-1` if this import is synthetic, does not have a
-   * prefix, or otherwise does not have an offset.
-   */
-  int get prefixOffset;
-}
-
-/**
- * A concrete implementation of an [ImportElement].
- */
-class ImportElementImpl extends UriReferencedElementImpl
-    implements ImportElement {
-  /**
-   * The offset of the prefix of this import in the file that contains the this
-   * import directive, or `-1` if this import is synthetic.
-   */
-  int prefixOffset = 0;
-
-  /**
-   * The library that is imported into this library by this import directive.
-   */
-  LibraryElement importedLibrary;
-
-  /**
-   * The combinators that were specified as part of the import directive in the
-   * order in which they were specified.
-   */
-  List<NamespaceCombinator> combinators = NamespaceCombinator.EMPTY_LIST;
-
-  /**
-   * The prefix that was specified as part of the import directive, or `null` if
-   * there was no prefix specified.
-   */
-  PrefixElement prefix;
-
-  /**
-   * Initialize a newly created import element at the given [offset].
-   * The offset may be `-1` if the import is synthetic.
-   */
-  ImportElementImpl(int offset) : super(null, offset);
-
-  /**
-   * Set whether this import is for a deferred library.
-   */
-  void set deferred(bool isDeferred) {
-    setModifier(Modifier.DEFERRED, isDeferred);
-  }
-
-  @override
-  String get identifier =>
-      "${(importedLibrary as LibraryElementImpl).identifier}@$nameOffset";
-
-  @override
-  bool get isDeferred => hasModifier(Modifier.DEFERRED);
-
-  @override
-  ElementKind get kind => ElementKind.IMPORT;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitImportElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write("import ");
-    (importedLibrary as LibraryElementImpl).appendTo(buffer);
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChild(prefix, visitor);
-  }
-}
-
-/**
- * The type introduced by either a class or an interface, or a reference to such
- * a type.
- */
-abstract class InterfaceType implements ParameterizedType {
-  /**
-   * An empty list of types.
-   */
-  @deprecated // Use InterfaceType.EMPTY_LIST
-  static const List<InterfaceType> EMPTY_ARRAY = const <InterfaceType>[];
-
-  /**
-   * An empty list of types.
-   */
-  static const List<InterfaceType> EMPTY_LIST = const <InterfaceType>[];
-
-  /**
-   * Return a list containing all of the accessors (getters and setters)
-   * declared in this type.
-   */
-  List<PropertyAccessorElement> get accessors;
-
-  /**
-   * Return a list containing all of the constructors declared in this type.
-   */
-  List<ConstructorElement> get constructors;
-
-  @override
-  ClassElement get element;
-
-  /**
-   * Return a list containing all of the interfaces that are implemented by this
-   * interface. Note that this is <b>not</b>, in general, equivalent to getting
-   * the interfaces from this type's element because the types returned by this
-   * method will have had their type parameters replaced.
-   */
-  List<InterfaceType> get interfaces;
-
-  /**
-   * Return a list containing all of the methods declared in this type.
-   */
-  List<MethodElement> get methods;
-
-  /**
-   * Return a list containing all of the mixins that are applied to the class
-   * being extended in order to derive the superclass of this class. Note that
-   * this is <b>not</b>, in general, equivalent to getting the mixins from this
-   * type's element because the types returned by this method will have had
-   * their type parameters replaced.
-   */
-  List<InterfaceType> get mixins;
-
-  /**
-   * Return the type representing the superclass of this type, or null if this
-   * type represents the class 'Object'. Note that this is <b>not</b>, in
-   * general, equivalent to getting the superclass from this type's element
-   * because the type returned by this method will have had it's type parameters
-   * replaced.
-   */
-  InterfaceType get superclass;
-
-  /**
-   * Return the element representing the getter with the given [name] that is
-   * declared in this class, or `null` if this class does not declare a getter
-   * with the given name.
-   */
-  PropertyAccessorElement getGetter(String name);
-
-  /**
-   * Return the least upper bound of this type and the given [type], or `null`
-   * if there is no least upper bound.
-   *
-   * Given two interfaces <i>I</i> and <i>J</i>, let <i>S<sub>I</sub></i> be the
-   * set of superinterfaces of <i>I<i>, let <i>S<sub>J</sub></i> be the set of
-   * superinterfaces of <i>J</i> and let <i>S = (I &cup; S<sub>I</sub>) &cap;
-   * (J &cup; S<sub>J</sub>)</i>. Furthermore, we define <i>S<sub>n</sub> =
-   * {T | T &isin; S &and; depth(T) = n}</i> for any finite <i>n</i>, where
-   * <i>depth(T)</i> is the number of steps in the longest inheritance path from
-   * <i>T</i> to <i>Object</i>. Let <i>q</i> be the largest number such that
-   * <i>S<sub>q</sub></i> has cardinality one. The least upper bound of <i>I</i>
-   * and <i>J</i> is the sole element of <i>S<sub>q</sub></i>.
-   */
-  @override
-  @deprecated
-  DartType getLeastUpperBound(DartType type);
-
-  /**
-   * Return the element representing the method with the given [name] that is
-   * declared in this class, or `null` if this class does not declare a method
-   * with the given name.
-   */
-  MethodElement getMethod(String name);
-
-  /**
-   * Return the element representing the setter with the given [name] that is
-   * declared in this class, or `null` if this class does not declare a setter
-   * with the given name.
-   */
-  PropertyAccessorElement getSetter(String name);
-
-  /**
-   * Return `true` if this type is a direct supertype of the given [type]. The
-   * implicit interface of class <i>I</i> is a direct supertype of the implicit
-   * interface of class <i>J</i> iff:
-   *
-   * * <i>I</i> is Object, and <i>J</i> has no extends clause.
-   * * <i>I</i> is listed in the extends clause of <i>J</i>.
-   * * <i>I</i> is listed in the implements clause of <i>J</i>.
-   * * <i>I</i> is listed in the with clause of <i>J</i>.
-   * * <i>J</i> is a mixin application of the mixin of <i>I</i>.
-   */
-  bool isDirectSupertypeOf(InterfaceType type);
-
-  /**
-   * Return `true` if this type is more specific than the given [type]. An
-   * interface type <i>T</i> is more specific than an interface type <i>S</i>,
-   * written <i>T &laquo; S</i>, if one of the following conditions is met:
-   *
-   * * Reflexivity: <i>T</i> is <i>S</i>.
-   * * <i>T</i> is bottom.
-   * * <i>S</i> is dynamic.
-   * * Direct supertype: <i>S</i> is a direct supertype of <i>T</i>.
-   * * <i>T</i> is a type parameter and <i>S</i> is the upper bound of <i>T</i>.
-   * * Covariance: <i>T</i> is of the form <i>I&lt;T<sub>1</sub>, &hellip;,
-   *   T<sub>n</sub>&gt;</i> and S</i> is of the form <i>I&lt;S<sub>1</sub>,
-   *   &hellip;, S<sub>n</sub>&gt;</i> and <i>T<sub>i</sub> &laquo;
-   *   S<sub>i</sub></i>, <i>1 <= i <= n</i>.
-   * * Transitivity: <i>T &laquo; U</i> and <i>U &laquo; S</i>.
-   */
-  @override
-  bool isMoreSpecificThan(DartType type);
-
-  /**
-   * Return `true` if this type is a subtype of the given [type]. An interface
-   * type <i>T</i> is a subtype of an interface type <i>S</i>, written <i>T</i>
-   * <: <i>S</i>, iff <i>[bottom/dynamic]T</i> &laquo; <i>S</i> (<i>T</i> is
-   * more specific than <i>S</i>). If an interface type <i>I</i> includes a
-   * method named <i>call()</i>, and the type of <i>call()</i> is the function
-   * type <i>F</i>, then <i>I</i> is considered to be a subtype of <i>F</i>.
-   */
-  @override
-  bool isSubtypeOf(DartType type);
-
-  /**
-   * Return the element representing the constructor that results from looking
-   * up the constructor with the given [name] in this class with respect to the
-   * given [library], or `null` if the look up fails. The behavior of this
-   * method is defined by the Dart Language Specification in section 12.11.1:
-   * <blockquote>
-   * If <i>e</i> is of the form <b>new</b> <i>T.id()</i> then let <i>q<i> be the
-   * constructor <i>T.id</i>, otherwise let <i>q<i> be the constructor <i>T<i>.
-   * Otherwise, if <i>q</i> is not defined or not accessible, a
-   * NoSuchMethodException is thrown.
-   * </blockquote>
-   */
-  ConstructorElement lookUpConstructor(String name, LibraryElement library);
-
-  /**
-   * Return the element representing the getter that results from looking up the
-   * getter with the given [name] in this class with respect to the given
-   * [library], or `null` if the look up fails. The behavior of this method is
-   * defined by the Dart Language Specification in section 12.15.1:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is:
-   * * If <i>C</i> declares an instance getter (respectively setter) named
-   *   <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
-   *   setter) is the result of the lookup. Otherwise, if <i>C</i> has a
-   *   superclass <i>S</i>, then the result of the lookup is the result of
-   *   looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
-   *   to <i>L</i>. Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpGetter(String name, LibraryElement library);
-
-  /**
-   * Return the element representing the getter that results from looking up the
-   * getter with the given [name] in the superclass of this class with respect
-   * to the given [library], or `null` if the look up fails. The behavior of
-   * this method is defined by the Dart Language Specification in section
-   * 12.15.1:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is:
-   * * If <i>C</i> declares an instance getter (respectively setter) named
-   *   <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
-   *   setter) is the result of the lookup. Otherwise, if <i>C</i> has a
-   *   superclass <i>S</i>, then the result of the lookup is the result of
-   *   looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
-   *   to <i>L</i>. Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpGetterInSuperclass(
-      String name, LibraryElement library);
-
-  /**
-   * Return the element representing the method that results from looking up the
-   * method with the given [name] in this class with respect to the given
-   * [library], or `null` if the look up fails. The behavior of this method is
-   * defined by the Dart Language Specification in section 12.15.1:
-   * <blockquote>
-   * The result of looking up method <i>m</i> in class <i>C</i> with respect to
-   * library <i>L</i> is:
-   * * If <i>C</i> declares an instance method named <i>m</i> that is accessible
-   *   to <i>L</i>, then that method is the result of the lookup. Otherwise, if
-   *   <i>C</i> has a superclass <i>S</i>, then the result of the lookup is the
-   *   result of looking up method <i>m</i> in <i>S</i> with respect to <i>L</i>
-   *   Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  MethodElement lookUpMethod(String name, LibraryElement library);
-
-  /**
-   * Return the element representing the method that results from looking up the
-   * method with the given [name] in the superclass of this class with respect
-   * to the given [library], or `null` if the look up fails. The behavior of
-   * this method is defined by the Dart Language Specification in section
-   * 12.15.1:
-   * <blockquote>
-   * The result of looking up method <i>m</i> in class <i>C</i> with respect to
-   * library <i>L</i> is:
-   * * If <i>C</i> declares an instance method named <i>m</i> that is accessible
-   *   to <i>L</i>, then that method is the result of the lookup. Otherwise, if
-   * <i>C</i> has a superclass <i>S</i>, then the result of the lookup is the
-   * result of looking up method <i>m</i> in <i>S</i> with respect to <i>L</i>.
-   * Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  MethodElement lookUpMethodInSuperclass(String name, LibraryElement library);
-
-  /**
-   * Return the element representing the setter that results from looking up the
-   * setter with the given [name] in this class with respect to the given
-   * [library], or `null` if the look up fails. The behavior of this method is
-   * defined by the Dart Language Specification in section 12.16:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is:
-   * * If <i>C</i> declares an instance getter (respectively setter) named
-   *   <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
-   *   setter) is the result of the lookup. Otherwise, if <i>C</i> has a
-   *   superclass <i>S</i>, then the result of the lookup is the result of
-   *   looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
-   *   to <i>L</i>. Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpSetter(String name, LibraryElement library);
-
-  /**
-   * Return the element representing the setter that results from looking up the
-   * setter with the given [name] in the superclass of this class with respect
-   * to the given [library], or `null` if the look up fails. The behavior of
-   * this method is defined by the Dart Language Specification in section 12.16:
-   * <blockquote>
-   * The result of looking up getter (respectively setter) <i>m</i> in class
-   * <i>C</i> with respect to library <i>L</i> is:
-   * * If <i>C</i> declares an instance getter (respectively setter) named
-   *   <i>m</i> that is accessible to <i>L</i>, then that getter (respectively
-   *   setter) is the result of the lookup. Otherwise, if <i>C</i> has a
-   *   superclass <i>S</i>, then the result of the lookup is the result of
-   *   looking up getter (respectively setter) <i>m</i> in <i>S</i> with respect
-   *   to <i>L</i>. Otherwise, we say that the lookup has failed.
-   * </blockquote>
-   */
-  PropertyAccessorElement lookUpSetterInSuperclass(
-      String name, LibraryElement library);
-
-  @override
-  InterfaceType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes);
-
-  /**
-   * Return the type resulting from substituting the given arguments for this
-   * type's parameters. This is fully equivalent to `substitute2(argumentTypes,
-   * getTypeArguments())`.
-   */
-  InterfaceType substitute4(List<DartType> argumentTypes);
-
-  /**
-   * Returns a "smart" version of the "least upper bound" of the given types.
-   *
-   * If these types have the same element and differ only in terms of the type
-   * arguments, attempts to find a compatible set of type arguments.
-   *
-   * Otherwise, calls [DartType.getLeastUpperBound].
-   */
-  static InterfaceType getSmartLeastUpperBound(
-      InterfaceType first, InterfaceType second) {
-    // TODO(paulberry): this needs to be deprecated and replaced with a method
-    // in [TypeSystem], since it relies on the deprecated functionality of
-    // [DartType.getLeastUpperBound].
-    if (first.element == second.element) {
-      return _leastUpperBound(first, second);
-    }
-    return first.getLeastUpperBound(second);
-  }
-
-  /**
-   * Return the "least upper bound" of the given types under the assumption that
-   * the types have the same element and differ only in terms of the type
-   * arguments.
-   *
-   * The resulting type is composed by comparing the corresponding type
-   * arguments, keeping those that are the same, and using 'dynamic' for those
-   * that are different.
-   */
-  static InterfaceType _leastUpperBound(
-      InterfaceType firstType, InterfaceType secondType) {
-    ClassElement firstElement = firstType.element;
-    ClassElement secondElement = secondType.element;
-    if (firstElement != secondElement) {
-      throw new IllegalArgumentException('The same elements expected, but '
-          '$firstElement and $secondElement are given.');
-    }
-    if (firstType == secondType) {
-      return firstType;
-    }
-    List<DartType> firstArguments = firstType.typeArguments;
-    List<DartType> secondArguments = secondType.typeArguments;
-    int argumentCount = firstArguments.length;
-    if (argumentCount == 0) {
-      return firstType;
-    }
-    List<DartType> lubArguments = new List<DartType>(argumentCount);
-    for (int i = 0; i < argumentCount; i++) {
-      //
-      // Ideally we would take the least upper bound of the two argument types,
-      // but this can cause an infinite recursion (such as when finding the
-      // least upper bound of String and num).
-      //
-      if (firstArguments[i] == secondArguments[i]) {
-        lubArguments[i] = firstArguments[i];
-      }
-      if (lubArguments[i] == null) {
-        lubArguments[i] = DynamicTypeImpl.instance;
-      }
-    }
-    InterfaceTypeImpl lub = new InterfaceTypeImpl(firstElement);
-    lub.typeArguments = lubArguments;
-    return lub;
-  }
-}
-
-/**
- * A concrete implementation of an [InterfaceType].
- */
-class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
-  /**
-   * A list containing the actual types of the type arguments.
-   */
-  List<DartType> typeArguments = DartType.EMPTY_LIST;
-
-  /**
-   * The set of typedefs which should not be expanded when exploring this type,
-   * to avoid creating infinite types in response to self-referential typedefs.
-   */
-  final List<FunctionTypeAliasElement> prunedTypedefs;
-
-  /**
-   * Initialize a newly created type to be declared by the given [element].
-   */
-  InterfaceTypeImpl(ClassElement element, [this.prunedTypedefs])
-      : super(element, element.displayName);
-
-  /**
-   * Initialize a newly created type to be declared by the given [element].
-   */
-  @deprecated // Use new InterfaceTypeImpl(element)
-  InterfaceTypeImpl.con1(ClassElement element)
-      : prunedTypedefs = null,
-        super(element, element.displayName);
-
-  /**
-   * Initialize a newly created type to have the given [name]. This constructor
-   * should only be used in cases where there is no declaration of the type.
-   */
-  @deprecated // Use new InterfaceTypeImpl.named(name)
-  InterfaceTypeImpl.con2(String name)
-      : prunedTypedefs = null,
-        super(null, name);
-
-  /**
-   * Initialize a newly created type to have the given [name]. This constructor
-   * should only be used in cases where there is no declaration of the type.
-   */
-  InterfaceTypeImpl.named(String name)
-      : prunedTypedefs = null,
-        super(null, name);
-
-  /**
-   * Private constructor.
-   */
-  InterfaceTypeImpl._(Element element, String name, this.prunedTypedefs)
-      : super(element, name);
-
-  @override
-  List<PropertyAccessorElement> get accessors {
-    List<PropertyAccessorElement> accessors = element.accessors;
-    List<PropertyAccessorElement> members =
-        new List<PropertyAccessorElement>(accessors.length);
-    for (int i = 0; i < accessors.length; i++) {
-      members[i] = PropertyAccessorMember.from(accessors[i], this);
-    }
-    return members;
-  }
-
-  @override
-  List<ConstructorElement> get constructors {
-    List<ConstructorElement> constructors = element.constructors;
-    List<ConstructorElement> members =
-        new List<ConstructorElement>(constructors.length);
-    for (int i = 0; i < constructors.length; i++) {
-      members[i] = ConstructorMember.from(constructors[i], this);
-    }
-    return members;
-  }
-
-  @override
-  String get displayName {
-    String name = this.name;
-    List<DartType> typeArguments = this.typeArguments;
-    bool allDynamic = true;
-    for (DartType type in typeArguments) {
-      if (type != null && !type.isDynamic) {
-        allDynamic = false;
-        break;
-      }
-    }
-    // If there is at least one non-dynamic type, then list them out
-    if (!allDynamic) {
-      StringBuffer buffer = new StringBuffer();
-      buffer.write(name);
-      buffer.write("<");
-      for (int i = 0; i < typeArguments.length; i++) {
-        if (i != 0) {
-          buffer.write(", ");
-        }
-        DartType typeArg = typeArguments[i];
-        buffer.write(typeArg.displayName);
-      }
-      buffer.write(">");
-      name = buffer.toString();
-    }
-    return name;
-  }
-
-  @override
-  ClassElement get element => super.element as ClassElement;
-
-  @override
-  int get hashCode {
-    ClassElement element = this.element;
-    if (element == null) {
-      return 0;
-    }
-    return element.hashCode;
-  }
-
-  @override
-  List<InterfaceType> get interfaces {
-    ClassElement classElement = element;
-    List<InterfaceType> interfaces = classElement.interfaces;
-    List<TypeParameterElement> typeParameters = classElement.typeParameters;
-    List<DartType> parameterTypes = classElement.type.typeArguments;
-    if (typeParameters.length == 0) {
-      return interfaces;
-    }
-    int count = interfaces.length;
-    List<InterfaceType> typedInterfaces = new List<InterfaceType>(count);
-    for (int i = 0; i < count; i++) {
-      typedInterfaces[i] =
-          interfaces[i].substitute2(typeArguments, parameterTypes);
-    }
-    return typedInterfaces;
-  }
-
-  @override
-  bool get isDartCoreFunction {
-    ClassElement element = this.element;
-    if (element == null) {
-      return false;
-    }
-    return element.name == "Function" && element.library.isDartCore;
-  }
-
-  @override
-  bool get isObject => element.supertype == null;
-
-  @override
-  List<MethodElement> get methods {
-    List<MethodElement> methods = element.methods;
-    List<MethodElement> members = new List<MethodElement>(methods.length);
-    for (int i = 0; i < methods.length; i++) {
-      members[i] = MethodMember.from(methods[i], this);
-    }
-    return members;
-  }
-
-  @override
-  List<InterfaceType> get mixins {
-    ClassElement classElement = element;
-    List<InterfaceType> mixins = classElement.mixins;
-    List<TypeParameterElement> typeParameters = classElement.typeParameters;
-    List<DartType> parameterTypes = classElement.type.typeArguments;
-    if (typeParameters.length == 0) {
-      return mixins;
-    }
-    int count = mixins.length;
-    List<InterfaceType> typedMixins = new List<InterfaceType>(count);
-    for (int i = 0; i < count; i++) {
-      typedMixins[i] = mixins[i].substitute2(typeArguments, parameterTypes);
-    }
-    return typedMixins;
-  }
-
-  @override
-  InterfaceType get superclass {
-    ClassElement classElement = element;
-    InterfaceType supertype = classElement.supertype;
-    if (supertype == null) {
-      return null;
-    }
-    List<DartType> typeParameters = classElement.type.typeArguments;
-    if (typeArguments.length == 0 ||
-        typeArguments.length != typeParameters.length) {
-      return supertype;
-    }
-    return supertype.substitute2(typeArguments, typeParameters);
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters => element.typeParameters;
-
-  @override
-  bool operator ==(Object object) {
-    if (identical(object, this)) {
-      return true;
-    }
-    if (object is! InterfaceTypeImpl) {
-      return false;
-    }
-    InterfaceTypeImpl otherType = object as InterfaceTypeImpl;
-    return (element == otherType.element) &&
-        TypeImpl.equalArrays(typeArguments, otherType.typeArguments);
-  }
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write(name);
-    int argumentCount = typeArguments.length;
-    if (argumentCount > 0) {
-      buffer.write("<");
-      for (int i = 0; i < argumentCount; i++) {
-        if (i > 0) {
-          buffer.write(", ");
-        }
-        (typeArguments[i] as TypeImpl).appendTo(buffer);
-      }
-      buffer.write(">");
-    }
-  }
-
-  @override
-  PropertyAccessorElement getGetter(String getterName) => PropertyAccessorMember
-      .from((element as ClassElementImpl).getGetter(getterName), this);
-
-  @override
-  @deprecated
-  DartType getLeastUpperBound(DartType type) {
-    // quick check for self
-    if (identical(type, this)) {
-      return this;
-    }
-    // dynamic
-    DartType dynamicType = DynamicTypeImpl.instance;
-    if (identical(this, dynamicType) || identical(type, dynamicType)) {
-      return dynamicType;
-    }
-    // TODO (jwren) opportunity here for a better, faster algorithm if this
-    // turns out to be a bottle-neck
-    if (type is! InterfaceType) {
-      return null;
-    }
-    return computeLeastUpperBound(this, type);
-  }
-
-  @override
-  MethodElement getMethod(String methodName) => MethodMember.from(
-      (element as ClassElementImpl).getMethod(methodName), this);
-
-  @override
-  PropertyAccessorElement getSetter(String setterName) => PropertyAccessorMember
-      .from((element as ClassElementImpl).getSetter(setterName), this);
-
-  @override
-  bool isDirectSupertypeOf(InterfaceType type) {
-    InterfaceType i = this;
-    InterfaceType j = type;
-    ClassElement jElement = j.element;
-    InterfaceType supertype = jElement.supertype;
-    //
-    // If J has no direct supertype then it is Object, and Object has no direct
-    // supertypes.
-    //
-    if (supertype == null) {
-      return false;
-    }
-    //
-    // I is listed in the extends clause of J.
-    //
-    List<DartType> jArgs = j.typeArguments;
-    List<DartType> jVars = jElement.type.typeArguments;
-    supertype = supertype.substitute2(jArgs, jVars);
-    if (supertype == i) {
-      return true;
-    }
-    //
-    // I is listed in the implements clause of J.
-    //
-    for (InterfaceType interfaceType in jElement.interfaces) {
-      interfaceType = interfaceType.substitute2(jArgs, jVars);
-      if (interfaceType == i) {
-        return true;
-      }
-    }
-    //
-    // I is listed in the with clause of J.
-    //
-    for (InterfaceType mixinType in jElement.mixins) {
-      mixinType = mixinType.substitute2(jArgs, jVars);
-      if (mixinType == i) {
-        return true;
-      }
-    }
-    //
-    // J is a mixin application of the mixin of I.
-    //
-    // TODO(brianwilkerson) Determine whether this needs to be implemented or
-    // whether it is covered by the case above.
-    return false;
-  }
-
-  @override
-  bool isMoreSpecificThan(DartType type,
-      [bool withDynamic = false, Set<Element> visitedElements]) {
-    //
-    // S is dynamic.
-    // The test to determine whether S is dynamic is done here because dynamic
-    // is not an instance of InterfaceType.
-    //
-    if (type.isDynamic) {
-      return true;
-    }
-    //
-    // A type T is more specific than a type S, written T << S,
-    // if one of the following conditions is met:
-    //
-    // Reflexivity: T is S.
-    //
-    if (this == type) {
-      return true;
-    }
-    if (type is InterfaceType) {
-      //
-      // T is bottom. (This case is handled by the class BottomTypeImpl.)
-      //
-      // Direct supertype: S is a direct supertype of T.
-      //
-      if (type.isDirectSupertypeOf(this)) {
-        return true;
-      }
-      //
-      // Covariance: T is of the form I<T1, ..., Tn> and S is of the form
-      // I<S1, ..., Sn> and Ti << Si, 1 <= i <= n.
-      //
-      ClassElement tElement = this.element;
-      ClassElement sElement = type.element;
-      if (tElement == sElement) {
-        List<DartType> tArguments = typeArguments;
-        List<DartType> sArguments = type.typeArguments;
-        if (tArguments.length != sArguments.length) {
-          return false;
-        }
-        for (int i = 0; i < tArguments.length; i++) {
-          if (!(tArguments[i] as TypeImpl).isMoreSpecificThan(
-              sArguments[i], withDynamic)) {
-            return false;
-          }
-        }
-        return true;
-      }
-    }
-    //
-    // Transitivity: T << U and U << S.
-    //
-    // First check for infinite loops
-    if (element == null) {
-      return false;
-    }
-    if (visitedElements == null) {
-      visitedElements = new HashSet<ClassElement>();
-    } else if (visitedElements.contains(element)) {
-      return false;
-    }
-    visitedElements.add(element);
-    try {
-      // Iterate over all of the types U that are more specific than T because
-      // they are direct supertypes of T and return true if any of them are more
-      // specific than S.
-      InterfaceTypeImpl supertype = superclass;
-      if (supertype != null &&
-          supertype.isMoreSpecificThan(type, withDynamic, visitedElements)) {
-        return true;
-      }
-      for (InterfaceType interfaceType in interfaces) {
-        if ((interfaceType as InterfaceTypeImpl).isMoreSpecificThan(
-            type, withDynamic, visitedElements)) {
-          return true;
-        }
-      }
-      for (InterfaceType mixinType in mixins) {
-        if ((mixinType as InterfaceTypeImpl).isMoreSpecificThan(
-            type, withDynamic, visitedElements)) {
-          return true;
-        }
-      }
-      // If a type I includes an instance method named `call`, and the type of
-      // `call` is the function type F, then I is considered to be more specific
-      // than F.
-      MethodElement callMethod = getMethod('call');
-      if (callMethod != null && !callMethod.isStatic) {
-        FunctionTypeImpl callType = callMethod.type;
-        if (callType.isMoreSpecificThan(type, withDynamic, visitedElements)) {
-          return true;
-        }
-      }
-      return false;
-    } finally {
-      visitedElements.remove(element);
-    }
-  }
-
-  @override
-  ConstructorElement lookUpConstructor(
-      String constructorName, LibraryElement library) {
-    // prepare base ConstructorElement
-    ConstructorElement constructorElement;
-    if (constructorName == null) {
-      constructorElement = element.unnamedConstructor;
-    } else {
-      constructorElement = element.getNamedConstructor(constructorName);
-    }
-    // not found or not accessible
-    if (constructorElement == null ||
-        !constructorElement.isAccessibleIn(library)) {
-      return null;
-    }
-    // return member
-    return ConstructorMember.from(constructorElement, this);
-  }
-
-  @override
-  PropertyAccessorElement lookUpGetter(
-      String getterName, LibraryElement library) {
-    PropertyAccessorElement element = getGetter(getterName);
-    if (element != null && element.isAccessibleIn(library)) {
-      return element;
-    }
-    return lookUpGetterInSuperclass(getterName, library);
-  }
-
-  @override
-  PropertyAccessorElement lookUpGetterInSuperclass(
-      String getterName, LibraryElement library) {
-    for (InterfaceType mixin in mixins.reversed) {
-      PropertyAccessorElement element = mixin.getGetter(getterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    InterfaceType supertype = superclass;
-    ClassElement supertypeElement =
-        supertype == null ? null : supertype.element;
-    while (supertype != null && !visitedClasses.contains(supertypeElement)) {
-      visitedClasses.add(supertypeElement);
-      PropertyAccessorElement element = supertype.getGetter(getterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-      for (InterfaceType mixin in supertype.mixins.reversed) {
-        element = mixin.getGetter(getterName);
-        if (element != null && element.isAccessibleIn(library)) {
-          return element;
-        }
-      }
-      supertype = supertype.superclass;
-      supertypeElement = supertype == null ? null : supertype.element;
-    }
-    return null;
-  }
-
-  @override
-  MethodElement lookUpMethod(String methodName, LibraryElement library) {
-    MethodElement element = getMethod(methodName);
-    if (element != null && element.isAccessibleIn(library)) {
-      return element;
-    }
-    return lookUpMethodInSuperclass(methodName, library);
-  }
-
-  @override
-  MethodElement lookUpMethodInSuperclass(
-      String methodName, LibraryElement library) {
-    for (InterfaceType mixin in mixins.reversed) {
-      MethodElement element = mixin.getMethod(methodName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    InterfaceType supertype = superclass;
-    ClassElement supertypeElement =
-        supertype == null ? null : supertype.element;
-    while (supertype != null && !visitedClasses.contains(supertypeElement)) {
-      visitedClasses.add(supertypeElement);
-      MethodElement element = supertype.getMethod(methodName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-      for (InterfaceType mixin in supertype.mixins.reversed) {
-        element = mixin.getMethod(methodName);
-        if (element != null && element.isAccessibleIn(library)) {
-          return element;
-        }
-      }
-      supertype = supertype.superclass;
-      supertypeElement = supertype == null ? null : supertype.element;
-    }
-    return null;
-  }
-
-  @override
-  PropertyAccessorElement lookUpSetter(
-      String setterName, LibraryElement library) {
-    PropertyAccessorElement element = getSetter(setterName);
-    if (element != null && element.isAccessibleIn(library)) {
-      return element;
-    }
-    return lookUpSetterInSuperclass(setterName, library);
-  }
-
-  @override
-  PropertyAccessorElement lookUpSetterInSuperclass(
-      String setterName, LibraryElement library) {
-    for (InterfaceType mixin in mixins.reversed) {
-      PropertyAccessorElement element = mixin.getSetter(setterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-    }
-    HashSet<ClassElement> visitedClasses = new HashSet<ClassElement>();
-    InterfaceType supertype = superclass;
-    ClassElement supertypeElement =
-        supertype == null ? null : supertype.element;
-    while (supertype != null && !visitedClasses.contains(supertypeElement)) {
-      visitedClasses.add(supertypeElement);
-      PropertyAccessorElement element = supertype.getSetter(setterName);
-      if (element != null && element.isAccessibleIn(library)) {
-        return element;
-      }
-      for (InterfaceType mixin in supertype.mixins.reversed) {
-        element = mixin.getSetter(setterName);
-        if (element != null && element.isAccessibleIn(library)) {
-          return element;
-        }
-      }
-      supertype = supertype.superclass;
-      supertypeElement = supertype == null ? null : supertype.element;
-    }
-    return null;
-  }
-
-  @override
-  InterfaceTypeImpl pruned(List<FunctionTypeAliasElement> prune) {
-    if (prune == null) {
-      return this;
-    } else {
-      // There should never be a reason to prune a type that has already been
-      // pruned, since pruning is only done when expanding a function type
-      // alias, and function type aliases are always expanded by starting with
-      // base types.
-      assert(this.prunedTypedefs == null);
-      InterfaceTypeImpl result = new InterfaceTypeImpl._(element, name, prune);
-      result.typeArguments =
-          typeArguments.map((TypeImpl t) => t.pruned(prune)).toList();
-      return result;
-    }
-  }
-
-  @override
-  InterfaceTypeImpl substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) {
-    // Pruned types should only ever result from performing type variable
-    // substitution, and it doesn't make sense to substitute again after
-    // substituting once.
-    assert(this.prunedTypedefs == null);
-    if (argumentTypes.length != parameterTypes.length) {
-      throw new IllegalArgumentException(
-          "argumentTypes.length (${argumentTypes.length}) != parameterTypes.length (${parameterTypes.length})");
-    }
-    if (argumentTypes.length == 0 || typeArguments.length == 0) {
-      return this.pruned(prune);
-    }
-    List<DartType> newTypeArguments = TypeImpl.substitute(
-        typeArguments, argumentTypes, parameterTypes, prune);
-    if (JavaArrays.equals(newTypeArguments, typeArguments)) {
-      return this;
-    }
-    InterfaceTypeImpl newType = new InterfaceTypeImpl(element, prune);
-    newType.typeArguments = newTypeArguments;
-    return newType;
-  }
-
-  @override
-  InterfaceTypeImpl substitute4(List<DartType> argumentTypes) =>
-      substitute2(argumentTypes, typeArguments);
-
-  /**
-   * Compute the least upper bound of types [i] and [j], both of which are
-   * known to be interface types.
-   *
-   * In the event that the algorithm fails (which might occur due to a bug in
-   * the analyzer), `null` is returned.
-   */
-  static InterfaceType computeLeastUpperBound(
-      InterfaceType i, InterfaceType j) {
-    // compute set of supertypes
-    Set<InterfaceType> si = computeSuperinterfaceSet(i);
-    Set<InterfaceType> sj = computeSuperinterfaceSet(j);
-    // union si with i and sj with j
-    si.add(i);
-    sj.add(j);
-    // compute intersection, reference as set 's'
-    List<InterfaceType> s = _intersection(si, sj);
-    // for each element in Set s, compute the largest inheritance path to Object
-    List<int> depths = new List<int>.filled(s.length, 0);
-    int maxDepth = 0;
-    for (int n = 0; n < s.length; n++) {
-      depths[n] = computeLongestInheritancePathToObject(s[n]);
-      if (depths[n] > maxDepth) {
-        maxDepth = depths[n];
-      }
-    }
-    // ensure that the currently computed maxDepth is unique,
-    // otherwise, decrement and test for uniqueness again
-    for (; maxDepth >= 0; maxDepth--) {
-      int indexOfLeastUpperBound = -1;
-      int numberOfTypesAtMaxDepth = 0;
-      for (int m = 0; m < depths.length; m++) {
-        if (depths[m] == maxDepth) {
-          numberOfTypesAtMaxDepth++;
-          indexOfLeastUpperBound = m;
-        }
-      }
-      if (numberOfTypesAtMaxDepth == 1) {
-        return s[indexOfLeastUpperBound];
-      }
-    }
-    // Should be impossible--there should always be exactly one type with the
-    // maximum depth.
-    assert(false);
-    return null;
-  }
-
-  /**
-   * Return the length of the longest inheritance path from the given [type] to
-   * Object.
-   *
-   * See [computeLeastUpperBound].
-   */
-  static int computeLongestInheritancePathToObject(InterfaceType type) =>
-      _computeLongestInheritancePathToObject(
-          type, 0, new HashSet<ClassElement>());
-
-  /**
-   * Returns the set of all superinterfaces of the given [type].
-   *
-   * See [computeLeastUpperBound].
-   */
-  static Set<InterfaceType> computeSuperinterfaceSet(InterfaceType type) =>
-      _computeSuperinterfaceSet(type, new HashSet<InterfaceType>());
-
-  /**
-   * Return the length of the longest inheritance path from a subtype of the
-   * given [type] to Object, where the given [depth] is the length of the
-   * longest path from the subtype to this type. The set of [visitedTypes] is
-   * used to prevent infinite recursion in the case of a cyclic type structure.
-   *
-   * See [computeLongestInheritancePathToObject], and [computeLeastUpperBound].
-   */
-  static int _computeLongestInheritancePathToObject(
-      InterfaceType type, int depth, HashSet<ClassElement> visitedTypes) {
-    ClassElement classElement = type.element;
-    // Object case
-    if (classElement.supertype == null || visitedTypes.contains(classElement)) {
-      return depth;
-    }
-    int longestPath = 1;
-    try {
-      visitedTypes.add(classElement);
-      List<InterfaceType> superinterfaces = classElement.interfaces;
-      int pathLength;
-      if (superinterfaces.length > 0) {
-        // loop through each of the superinterfaces recursively calling this
-        // method and keeping track of the longest path to return
-        for (InterfaceType superinterface in superinterfaces) {
-          pathLength = _computeLongestInheritancePathToObject(
-              superinterface, depth + 1, visitedTypes);
-          if (pathLength > longestPath) {
-            longestPath = pathLength;
-          }
-        }
-      }
-      // finally, perform this same check on the super type
-      // TODO(brianwilkerson) Does this also need to add in the number of mixin
-      // classes?
-      InterfaceType supertype = classElement.supertype;
-      pathLength = _computeLongestInheritancePathToObject(
-          supertype, depth + 1, visitedTypes);
-      if (pathLength > longestPath) {
-        longestPath = pathLength;
-      }
-    } finally {
-      visitedTypes.remove(classElement);
-    }
-    return longestPath;
-  }
-
-  /**
-   * Add all of the superinterfaces of the given [type] to the given [set].
-   * Return the [set] as a convenience.
-   *
-   * See [computeSuperinterfaceSet], and [computeLeastUpperBound].
-   */
-  static Set<InterfaceType> _computeSuperinterfaceSet(
-      InterfaceType type, HashSet<InterfaceType> set) {
-    Element element = type.element;
-    if (element != null) {
-      List<InterfaceType> superinterfaces = type.interfaces;
-      for (InterfaceType superinterface in superinterfaces) {
-        if (set.add(superinterface)) {
-          _computeSuperinterfaceSet(superinterface, set);
-        }
-      }
-      InterfaceType supertype = type.superclass;
-      if (supertype != null) {
-        if (set.add(supertype)) {
-          _computeSuperinterfaceSet(supertype, set);
-        }
-      }
-    }
-    return set;
-  }
-
-  /**
-   * Return the intersection of the [first] and [second] sets of types, where
-   * intersection is based on the equality of the types themselves.
-   */
-  static List<InterfaceType> _intersection(
-      Set<InterfaceType> first, Set<InterfaceType> second) {
-    Set<InterfaceType> result = new HashSet<InterfaceType>.from(first);
-    result.retainAll(second);
-    return new List.from(result);
-  }
-}
-
-/**
- * A label associated with a statement.
- */
-abstract class LabelElement implements Element {
-  /**
-   * An empty list of label elements.
-   */
-  static const List<LabelElement> EMPTY_LIST = const <LabelElement>[];
-
-  /**
-   * Return the executable element in which this label is defined.
-   */
-  @override
-  ExecutableElement get enclosingElement;
-}
-
-/**
- * A concrete implementation of a [LabelElement].
- */
-class LabelElementImpl extends ElementImpl implements LabelElement {
-  /**
-   * An empty list of label elements.
-   */
-  @deprecated // Use LabelElement.EMPTY_LIST
-  static const List<LabelElement> EMPTY_ARRAY = const <LabelElement>[];
-
-  /**
-   * A flag indicating whether this label is associated with a `switch`
-   * statement.
-   */
-  // TODO(brianwilkerson) Make this a modifier.
-  final bool _onSwitchStatement;
-
-  /**
-   * A flag indicating whether this label is associated with a `switch` member
-   * (`case` or `default`).
-   */
-  // TODO(brianwilkerson) Make this a modifier.
-  final bool _onSwitchMember;
-
-  /**
-   * Initialize a newly created label element to have the given [name].
-   * [onSwitchStatement] should be `true` if this label is associated with a
-   * `switch` statement and [onSwitchMember] should be `true` if this label is
-   * associated with a `switch` member.
-   */
-  LabelElementImpl(
-      Identifier name, this._onSwitchStatement, this._onSwitchMember)
-      : super.forNode(name);
-
-  @override
-  ExecutableElement get enclosingElement =>
-      super.enclosingElement as ExecutableElement;
-
-  /**
-   * Return `true` if this label is associated with a `switch` member (`case` or
-   * `default`).
-   */
-  bool get isOnSwitchMember => _onSwitchMember;
-
-  /**
-   * Return `true` if this label is associated with a `switch` statement.
-   */
-  bool get isOnSwitchStatement => _onSwitchStatement;
-
-  @override
-  ElementKind get kind => ElementKind.LABEL;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitLabelElement(this);
-}
-
-/**
- * A library.
- */
-abstract class LibraryElement implements Element {
-  /**
-   * An empty list of library elements.
-   */
-  static const List<LibraryElement> EMPTY_LIST = const <LibraryElement>[];
-
-  /**
-   * Return the compilation unit that defines this library.
-   */
-  CompilationUnitElement get definingCompilationUnit;
-
-  /**
-   * Return the entry point for this library, or `null` if this library does not
-   * have an entry point. The entry point is defined to be a zero argument
-   * top-level function whose name is `main`.
-   */
-  FunctionElement get entryPoint;
-
-  /**
-   * Return a list containing all of the libraries that are exported from this
-   * library.
-   */
-  List<LibraryElement> get exportedLibraries;
-
-  /**
-   * The export [Namespace] of this library, `null` if it has not been
-   * computed yet.
-   */
-  Namespace get exportNamespace;
-
-  /**
-   * Return a list containing all of the exports defined in this library.
-   */
-  List<ExportElement> get exports;
-
-  /**
-   * Return `true` if the defining compilation unit of this library contains at
-   * least one import directive whose URI uses the "dart-ext" scheme.
-   */
-  bool get hasExtUri;
-
-  /**
-   * Return `true` if this library defines a top-level function named
-   * `loadLibrary`.
-   */
-  bool get hasLoadLibraryFunction;
-
-  /**
-   * Return a list containing all of the libraries that are imported into this
-   * library. This includes all of the libraries that are imported using a
-   * prefix (also available through the prefixes returned by [getPrefixes]) and
-   * those that are imported without a prefix.
-   */
-  List<LibraryElement> get importedLibraries;
-
-  /**
-   * Return a list containing all of the imports defined in this library.
-   */
-  List<ImportElement> get imports;
-
-  /**
-   * Return `true` if this library is an application that can be run in the
-   * browser.
-   */
-  bool get isBrowserApplication;
-
-  /**
-   * Return `true` if this library is the dart:core library.
-   */
-  bool get isDartCore;
-
-  /**
-   * Return `true` if this library is part of the SDK.
-   */
-  bool get isInSdk;
-
-  /**
-   * Return the element representing the synthetic function `loadLibrary` that
-   * is implicitly defined for this library if the library is imported using a
-   * deferred import.
-   */
-  FunctionElement get loadLibraryFunction;
-
-  /**
-   * Return a list containing all of the compilation units that are included in
-   * this library using a `part` directive. This does not include the defining
-   * compilation unit that contains the `part` directives.
-   */
-  List<CompilationUnitElement> get parts;
-
-  /**
-   * Return a list containing elements for each of the prefixes used to `import`
-   * libraries into this library. Each prefix can be used in more than one
-   * `import` directive.
-   */
-  List<PrefixElement> get prefixes;
-
-  /**
-   * The public [Namespace] of this library, `null` if it has not been
-   * computed yet.
-   */
-  Namespace get publicNamespace;
-
-  /**
-   * Return a list containing all of the compilation units this library consists
-   * of. This includes the defining compilation unit and units included using
-   * the `part` directive.
-   */
-  List<CompilationUnitElement> get units;
-
-  /**
-   * Return a list containing all directly and indirectly imported libraries.
-   */
-  List<LibraryElement> get visibleLibraries;
-
-  /**
-   * Return a list containing all of the imports that share the given [prefix],
-   * or an empty array if there are no such imports.
-   */
-  List<ImportElement> getImportsWithPrefix(PrefixElement prefix);
-
-  /**
-   * Return the class defined in this library that has the given [name], or
-   * `null` if this library does not define a class with the given name.
-   */
-  ClassElement getType(String className);
-
-  /**
-   * Return `true` if this library is up to date with respect to the given
-   * [timeStamp]. If any transitively referenced Source is newer than the time
-   * stamp, this method returns false.
-   */
-  bool isUpToDate(int timeStamp);
-}
-
-/**
- * A concrete implementation of a [LibraryElement].
- */
-class LibraryElementImpl extends ElementImpl implements LibraryElement {
-  /**
-   * An empty list of library elements.
-   */
-  @deprecated // Use LibraryElement.EMPTY_LIST
-  static const List<LibraryElement> EMPTY_ARRAY = const <LibraryElement>[];
-
-  /**
-   * The analysis context in which this library is defined.
-   */
-  final AnalysisContext context;
-
-  /**
-   * The compilation unit that defines this library.
-   */
-  CompilationUnitElement _definingCompilationUnit;
-
-  /**
-   * The entry point for this library, or `null` if this library does not have
-   * an entry point.
-   */
-  FunctionElement entryPoint;
-
-  /**
-   * A list containing specifications of all of the imports defined in this
-   * library.
-   */
-  List<ImportElement> _imports = ImportElement.EMPTY_LIST;
-
-  /**
-   * A list containing specifications of all of the exports defined in this
-   * library.
-   */
-  List<ExportElement> _exports = ExportElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the compilation units that are included in this
-   * library using a `part` directive.
-   */
-  List<CompilationUnitElement> _parts = CompilationUnitElement.EMPTY_LIST;
-
-  /**
-   * The element representing the synthetic function `loadLibrary` that is
-   * defined for this library, or `null` if the element has not yet been created.
-   */
-  FunctionElement _loadLibraryFunction;
-
-  /**
-   * The export [Namespace] of this library, `null` if it has not been
-   * computed yet.
-   */
-  @override
-  Namespace exportNamespace;
-
-  /**
-   * The public [Namespace] of this library, `null` if it has not been
-   * computed yet.
-   */
-  @override
-  Namespace publicNamespace;
-
-  /**
-   * Initialize a newly created library element in the given [context] to have
-   * the given [name] and [offset].
-   */
-  LibraryElementImpl(this.context, String name, int offset)
-      : super(name, offset);
-
-  /**
-   * Initialize a newly created library element in the given [context] to have
-   * the given [name].
-   */
-  LibraryElementImpl.forNode(this.context, LibraryIdentifier name)
-      : super.forNode(name);
-
-  @override
-  CompilationUnitElement get definingCompilationUnit =>
-      _definingCompilationUnit;
-
-  /**
-   * Set the compilation unit that defines this library to the given compilation
-   * [unit].
-   */
-  void set definingCompilationUnit(CompilationUnitElement unit) {
-    assert((unit as CompilationUnitElementImpl).librarySource == unit.source);
-    (unit as CompilationUnitElementImpl).enclosingElement = this;
-    this._definingCompilationUnit = unit;
-  }
-
-  @override
-  List<LibraryElement> get exportedLibraries {
-    HashSet<LibraryElement> libraries = new HashSet<LibraryElement>();
-    for (ExportElement element in _exports) {
-      LibraryElement library = element.exportedLibrary;
-      if (library != null) {
-        libraries.add(library);
-      }
-    }
-    return new List.from(libraries);
-  }
-
-  @override
-  List<ExportElement> get exports => _exports;
-
-  /**
-   * Set the specifications of all of the exports defined in this library to the
-   * given list of [exports].
-   */
-  void set exports(List<ExportElement> exports) {
-    for (ExportElement exportElement in exports) {
-      (exportElement as ExportElementImpl).enclosingElement = this;
-    }
-    this._exports = exports;
-  }
-
-  @override
-  bool get hasExtUri => hasModifier(Modifier.HAS_EXT_URI);
-
-  /**
-   * Set whether this library has an import of a "dart-ext" URI.
-   */
-  void set hasExtUri(bool hasExtUri) {
-    setModifier(Modifier.HAS_EXT_URI, hasExtUri);
-  }
-
-  @override
-  int get hashCode => _definingCompilationUnit.hashCode;
-
-  @override
-  bool get hasLoadLibraryFunction {
-    if (_definingCompilationUnit.hasLoadLibraryFunction) {
-      return true;
-    }
-    for (int i = 0; i < _parts.length; i++) {
-      if (_parts[i].hasLoadLibraryFunction) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  String get identifier => _definingCompilationUnit.source.encoding;
-
-  @override
-  List<LibraryElement> get importedLibraries {
-    HashSet<LibraryElement> libraries = new HashSet<LibraryElement>();
-    for (ImportElement element in _imports) {
-      LibraryElement library = element.importedLibrary;
-      if (library != null) {
-        libraries.add(library);
-      }
-    }
-    return new List.from(libraries);
-  }
-
-  @override
-  List<ImportElement> get imports => _imports;
-
-  /**
-   * Set the specifications of all of the imports defined in this library to the
-   * given list of [imports].
-   */
-  void set imports(List<ImportElement> imports) {
-    for (ImportElement importElement in imports) {
-      (importElement as ImportElementImpl).enclosingElement = this;
-      PrefixElementImpl prefix = importElement.prefix as PrefixElementImpl;
-      if (prefix != null) {
-        prefix.enclosingElement = this;
-      }
-    }
-    this._imports = imports;
-  }
-
-  @override
-  bool get isBrowserApplication =>
-      entryPoint != null && isOrImportsBrowserLibrary;
-
-  @override
-  bool get isDartCore => name == "dart.core";
-
-  @override
-  bool get isInSdk =>
-      StringUtilities.startsWith5(name, 0, 0x64, 0x61, 0x72, 0x74, 0x2E);
-
-  /**
-   * Return `true` if the receiver directly or indirectly imports the
-   * 'dart:html' libraries.
-   */
-  bool get isOrImportsBrowserLibrary {
-    List<LibraryElement> visited = new List<LibraryElement>();
-    Source htmlLibSource = context.sourceFactory.forUri(DartSdk.DART_HTML);
-    visited.add(this);
-    for (int index = 0; index < visited.length; index++) {
-      LibraryElement library = visited[index];
-      Source source = library.definingCompilationUnit.source;
-      if (source == htmlLibSource) {
-        return true;
-      }
-      for (LibraryElement importedLibrary in library.importedLibraries) {
-        if (!visited.contains(importedLibrary)) {
-          visited.add(importedLibrary);
-        }
-      }
-      for (LibraryElement exportedLibrary in library.exportedLibraries) {
-        if (!visited.contains(exportedLibrary)) {
-          visited.add(exportedLibrary);
-        }
-      }
-    }
-    return false;
-  }
-
-  @override
-  ElementKind get kind => ElementKind.LIBRARY;
-
-  @override
-  LibraryElement get library => this;
-
-  @override
-  FunctionElement get loadLibraryFunction {
-    if (_loadLibraryFunction == null) {
-      FunctionElementImpl function =
-          new FunctionElementImpl(FunctionElement.LOAD_LIBRARY_NAME, -1);
-      function.synthetic = true;
-      function.enclosingElement = this;
-      function.returnType = loadLibraryReturnType;
-      function.type = new FunctionTypeImpl(function);
-      _loadLibraryFunction = function;
-    }
-    return _loadLibraryFunction;
-  }
-
-  /**
-   * Return the object representing the type 'Future' from the 'dart:async'
-   * library, or the type 'void' if the type 'Future' cannot be accessed.
-   */
-  DartType get loadLibraryReturnType {
-    try {
-      Source asyncSource = context.sourceFactory.forUri(DartSdk.DART_ASYNC);
-      if (asyncSource == null) {
-        AnalysisEngine.instance.logger
-            .logError("Could not create a source for dart:async");
-        return VoidTypeImpl.instance;
-      }
-      LibraryElement asyncElement = context.computeLibraryElement(asyncSource);
-      if (asyncElement == null) {
-        AnalysisEngine.instance.logger
-            .logError("Could not build the element model for dart:async");
-        return VoidTypeImpl.instance;
-      }
-      ClassElement futureElement = asyncElement.getType("Future");
-      if (futureElement == null) {
-        AnalysisEngine.instance.logger
-            .logError("Could not find type Future in dart:async");
-        return VoidTypeImpl.instance;
-      }
-      InterfaceType futureType = futureElement.type;
-      return futureType.substitute4(<DartType>[DynamicTypeImpl.instance]);
-    } on AnalysisException catch (exception, stackTrace) {
-      AnalysisEngine.instance.logger.logError(
-          "Could not build the element model for dart:async",
-          new CaughtException(exception, stackTrace));
-      return VoidTypeImpl.instance;
-    }
-  }
-
-  @override
-  List<CompilationUnitElement> get parts => _parts;
-
-  /**
-   * Set the compilation units that are included in this library using a `part`
-   * directive to the given list of [parts].
-   */
-  void set parts(List<CompilationUnitElement> parts) {
-    for (CompilationUnitElement compilationUnit in parts) {
-      assert((compilationUnit as CompilationUnitElementImpl).librarySource ==
-          source);
-      (compilationUnit as CompilationUnitElementImpl).enclosingElement = this;
-    }
-    this._parts = parts;
-  }
-
-  @override
-  List<PrefixElement> get prefixes {
-    HashSet<PrefixElement> prefixes = new HashSet<PrefixElement>();
-    for (ImportElement element in _imports) {
-      PrefixElement prefix = element.prefix;
-      if (prefix != null) {
-        prefixes.add(prefix);
-      }
-    }
-    return new List.from(prefixes);
-  }
-
-  @override
-  Source get source {
-    if (_definingCompilationUnit == null) {
-      return null;
-    }
-    return _definingCompilationUnit.source;
-  }
-
-  @override
-  List<CompilationUnitElement> get units {
-    List<CompilationUnitElement> units = new List<CompilationUnitElement>();
-    units.add(_definingCompilationUnit);
-    units.addAll(_parts);
-    return units;
-  }
-
-  @override
-  List<LibraryElement> get visibleLibraries {
-    Set<LibraryElement> visibleLibraries = new Set();
-    _addVisibleLibraries(visibleLibraries, false);
-    return new List.from(visibleLibraries);
-  }
-
-  @override
-  bool operator ==(Object object) => object is LibraryElementImpl &&
-      _definingCompilationUnit == object.definingCompilationUnit;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitLibraryElement(this);
-
-  @override
-  ElementImpl getChild(String identifier) {
-    if ((_definingCompilationUnit as CompilationUnitElementImpl).identifier ==
-        identifier) {
-      return _definingCompilationUnit as CompilationUnitElementImpl;
-    }
-    for (CompilationUnitElement part in _parts) {
-      if ((part as CompilationUnitElementImpl).identifier == identifier) {
-        return part as CompilationUnitElementImpl;
-      }
-    }
-    for (ImportElement importElement in _imports) {
-      if ((importElement as ImportElementImpl).identifier == identifier) {
-        return importElement as ImportElementImpl;
-      }
-    }
-    for (ExportElement exportElement in _exports) {
-      if ((exportElement as ExportElementImpl).identifier == identifier) {
-        return exportElement as ExportElementImpl;
-      }
-    }
-    return null;
-  }
-
-  @override
-  List<ImportElement> getImportsWithPrefix(PrefixElement prefixElement) {
-    int count = _imports.length;
-    List<ImportElement> importList = new List<ImportElement>();
-    for (int i = 0; i < count; i++) {
-      if (identical(_imports[i].prefix, prefixElement)) {
-        importList.add(_imports[i]);
-      }
-    }
-    return importList;
-  }
-
-  @override
-  ClassElement getType(String className) {
-    ClassElement type = _definingCompilationUnit.getType(className);
-    if (type != null) {
-      return type;
-    }
-    for (CompilationUnitElement part in _parts) {
-      type = part.getType(className);
-      if (type != null) {
-        return type;
-      }
-    }
-    return null;
-  }
-
-  @override
-  bool isUpToDate(int timeStamp) {
-    Set<LibraryElement> visitedLibraries = new Set();
-    return _safeIsUpToDate(this, timeStamp, visitedLibraries);
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChild(_definingCompilationUnit, visitor);
-    safelyVisitChildren(_exports, visitor);
-    safelyVisitChildren(_imports, visitor);
-    safelyVisitChildren(_parts, visitor);
-  }
-
-  /**
-   * Recursively fills set of visible libraries for
-   * [getVisibleElementsLibraries].
-   */
-  void _addVisibleLibraries(
-      Set<LibraryElement> visibleLibraries, bool includeExports) {
-    // maybe already processed
-    if (!visibleLibraries.add(this)) {
-      return;
-    }
-    // add imported libraries
-    for (ImportElement importElement in _imports) {
-      LibraryElement importedLibrary = importElement.importedLibrary;
-      if (importedLibrary != null) {
-        (importedLibrary as LibraryElementImpl)._addVisibleLibraries(
-            visibleLibraries, true);
-      }
-    }
-    // add exported libraries
-    if (includeExports) {
-      for (ExportElement exportElement in _exports) {
-        LibraryElement exportedLibrary = exportElement.exportedLibrary;
-        if (exportedLibrary != null) {
-          (exportedLibrary as LibraryElementImpl)._addVisibleLibraries(
-              visibleLibraries, true);
-        }
-      }
-    }
-  }
-
-  /**
-   * Return `true` if the given [library] is up to date with respect to the
-   * given [timeStamp]. The set of [visitedLibraries] is used to prevent
-   * infinite recusion in the case of mutually dependent libraries.
-   */
-  static bool _safeIsUpToDate(LibraryElement library, int timeStamp,
-      Set<LibraryElement> visitedLibraries) {
-    if (!visitedLibraries.contains(library)) {
-      visitedLibraries.add(library);
-      AnalysisContext context = library.context;
-      // Check the defining compilation unit.
-      if (timeStamp <
-          context
-              .getModificationStamp(library.definingCompilationUnit.source)) {
-        return false;
-      }
-      // Check the parted compilation units.
-      for (CompilationUnitElement element in library.parts) {
-        if (timeStamp < context.getModificationStamp(element.source)) {
-          return false;
-        }
-      }
-      // Check the imported libraries.
-      for (LibraryElement importedLibrary in library.importedLibraries) {
-        if (!_safeIsUpToDate(importedLibrary, timeStamp, visitedLibraries)) {
-          return false;
-        }
-      }
-      // Check the exported libraries.
-      for (LibraryElement exportedLibrary in library.exportedLibraries) {
-        if (!_safeIsUpToDate(exportedLibrary, timeStamp, visitedLibraries)) {
-          return false;
-        }
-      }
-    }
-    return true;
-  }
-}
-
-/**
- * An element that can be (but are not required to be) defined within a method
- * or function (an [ExecutableElement]).
- */
-abstract class LocalElement implements Element {
-  /**
-   * Return a source range that covers the approximate portion of the source in
-   * which the name of this element is visible, or `null` if there is no single
-   * range of characters within which the element name is visible.
-   *
-   * * For a local variable, this includes everything from the end of the
-   *   variable's initializer to the end of the block that encloses the variable
-   *   declaration.
-   * * For a parameter, this includes the body of the method or function that
-   *   declares the parameter.
-   * * For a local function, this includes everything from the beginning of the
-   *   function's body to the end of the block that encloses the function
-   *   declaration.
-   * * For top-level functions, `null` will be returned because they are
-   *   potentially visible in multiple sources.
-   */
-  SourceRange get visibleRange;
-}
-
-/**
- * A local variable.
- */
-abstract class LocalVariableElement implements LocalElement, VariableElement {
-  /**
-   * An empty list of field elements.
-   */
-  static const List<LocalVariableElement> EMPTY_LIST =
-      const <LocalVariableElement>[];
-
-  /**
-   * Return the resolved [VariableDeclaration] node that declares this
-   * [LocalVariableElement].
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  VariableDeclaration computeNode();
-}
-
-/**
- * A concrete implementation of a [LocalVariableElement].
- */
-class LocalVariableElementImpl extends VariableElementImpl
-    with PotentiallyConstVariableElement implements LocalVariableElement {
-  /**
-   * An empty list of field elements.
-   */
-  @deprecated // Use LocalVariableElement.EMPTY_LIST
-  static const List<LocalVariableElement> EMPTY_ARRAY =
-      const <LocalVariableElement>[];
-
-  /**
-   * The offset to the beginning of the visible range for this element.
-   */
-  int _visibleRangeOffset = 0;
-
-  /**
-   * The length of the visible range for this element, or `-1` if this element
-   * does not have a visible range.
-   */
-  int _visibleRangeLength = -1;
-
-  /**
-   * Initialize a newly created method element to have the given [name] and
-   * [offset].
-   */
-  LocalVariableElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created local variable element to have the given [name].
-   */
-  LocalVariableElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  String get identifier {
-    int enclosingOffset =
-        enclosingElement != null ? enclosingElement.nameOffset : 0;
-    int delta = nameOffset - enclosingOffset;
-    return '${super.identifier}@$delta';
-  }
-
-  @override
-  bool get isPotentiallyMutatedInClosure =>
-      hasModifier(Modifier.POTENTIALLY_MUTATED_IN_CONTEXT);
-
-  @override
-  bool get isPotentiallyMutatedInScope =>
-      hasModifier(Modifier.POTENTIALLY_MUTATED_IN_SCOPE);
-
-  @override
-  ElementKind get kind => ElementKind.LOCAL_VARIABLE;
-
-  @override
-  SourceRange get visibleRange {
-    if (_visibleRangeLength < 0) {
-      return null;
-    }
-    return new SourceRange(_visibleRangeOffset, _visibleRangeLength);
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitLocalVariableElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write(type);
-    buffer.write(" ");
-    buffer.write(displayName);
-  }
-
-  @override
-  VariableDeclaration computeNode() =>
-      getNodeMatching((node) => node is VariableDeclaration);
-
-  /**
-   * Specifies that this variable is potentially mutated somewhere in closure.
-   */
-  void markPotentiallyMutatedInClosure() {
-    setModifier(Modifier.POTENTIALLY_MUTATED_IN_CONTEXT, true);
-  }
-
-  /**
-   * Specifies that this variable is potentially mutated somewhere in its scope.
-   */
-  void markPotentiallyMutatedInScope() {
-    setModifier(Modifier.POTENTIALLY_MUTATED_IN_SCOPE, true);
-  }
-
-  /**
-   * Set the visible range for this element to the range starting at the given
-   * [offset] with the given [length].
-   */
-  void setVisibleRange(int offset, int length) {
-    _visibleRangeOffset = offset;
-    _visibleRangeLength = length;
-  }
-}
-
-/**
- * An element defined in a parameterized type where the values of the type
- * parameters are known.
- */
-abstract class Member implements Element {
-  /**
-   * The element on which the parameterized element was created.
-   */
-  final Element _baseElement;
-
-  /**
-   * The type in which the element is defined.
-   */
-  final ParameterizedType _definingType;
-
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  Member(this._baseElement, this._definingType);
-
-  /**
-   * Return the element on which the parameterized element was created.
-   */
-  Element get baseElement => _baseElement;
-
-  @override
-  AnalysisContext get context => _baseElement.context;
-
-  /**
-   * Return the type in which the element is defined.
-   */
-  ParameterizedType get definingType => _definingType;
-
-  @override
-  String get displayName => _baseElement.displayName;
-
-  int get id => _baseElement.id;
-
-  @override
-  bool get isDeprecated => _baseElement.isDeprecated;
-
-  @override
-  bool get isOverride => _baseElement.isOverride;
-
-  @override
-  bool get isPrivate => _baseElement.isPrivate;
-
-  @override
-  bool get isPublic => _baseElement.isPublic;
-
-  @override
-  bool get isSynthetic => _baseElement.isSynthetic;
-
-  @override
-  ElementKind get kind => _baseElement.kind;
-
-  @override
-  LibraryElement get library => _baseElement.library;
-
-  @override
-  ElementLocation get location => _baseElement.location;
-
-  @override
-  List<ElementAnnotation> get metadata => _baseElement.metadata;
-
-  @override
-  String get name => _baseElement.name;
-
-  @override
-  int get nameOffset => _baseElement.nameOffset;
-
-  @deprecated
-  @override
-  AstNode get node => computeNode();
-
-  @override
-  Source get source => _baseElement.source;
-
-  @override
-  CompilationUnit get unit => _baseElement.unit;
-
-  @override
-  String computeDocumentationComment() =>
-      _baseElement.computeDocumentationComment();
-
-  @override
-  AstNode computeNode() => _baseElement.computeNode();
-
-  @override
-  Element getAncestor(Predicate<Element> predicate) =>
-      baseElement.getAncestor(predicate);
-
-  @override
-  String getExtendedDisplayName(String shortName) =>
-      _baseElement.getExtendedDisplayName(shortName);
-
-  @override
-  bool isAccessibleIn(LibraryElement library) =>
-      _baseElement.isAccessibleIn(library);
-
-  /**
-   * If the given [child] is not `null`, use the given [visitor] to visit it.
-   */
-  void safelyVisitChild(Element child, ElementVisitor visitor) {
-    // TODO(brianwilkerson) Make this private
-    if (child != null) {
-      child.accept(visitor);
-    }
-  }
-
-  /**
-   * Use the given [visitor] to visit all of the [children].
-   */
-  void safelyVisitChildren(List<Element> children, ElementVisitor visitor) {
-    // TODO(brianwilkerson) Make this private
-    if (children != null) {
-      for (Element child in children) {
-        child.accept(visitor);
-      }
-    }
-  }
-
-  /**
-   * Return the type that results from replacing the type parameters in the
-   * given [type] with the type arguments associated with this member.
-   */
-  DartType substituteFor(DartType type) {
-    if (type == null) {
-      return null;
-    }
-    List<DartType> argumentTypes = _definingType.typeArguments;
-    List<DartType> parameterTypes =
-        TypeParameterTypeImpl.getTypes(_definingType.typeParameters);
-    return type.substitute2(argumentTypes, parameterTypes);
-  }
-
-  /**
-   * Return the list of types that results from replacing the type parameters in
-   * the given [types] with the type arguments associated with this member.
-   */
-  List<InterfaceType> substituteFor2(List<InterfaceType> types) {
-    int count = types.length;
-    List<InterfaceType> substitutedTypes = new List<InterfaceType>(count);
-    for (int i = 0; i < count; i++) {
-      substitutedTypes[i] = substituteFor(types[i]);
-    }
-    return substitutedTypes;
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    // There are no children to visit
-  }
-}
-
-/**
- * An element that represents a method defined within a type.
- */
-abstract class MethodElement implements ClassMemberElement, ExecutableElement {
-  /**
-   * An empty list of method elements.
-   */
-  static const List<MethodElement> EMPTY_LIST = const <MethodElement>[];
-
-  /**
-   * Return the resolved [MethodDeclaration] node that declares this
-   * [MethodElement].
-   *
-   * This method is expensive, because resolved AST might be evicted from cache,
-   * so parsing and resolving will be performed.
-   */
-  @override
-  MethodDeclaration computeNode();
-}
-
-/**
- * A concrete implementation of a [MethodElement].
- */
-class MethodElementImpl extends ExecutableElementImpl implements MethodElement {
-  /**
-   * An empty list of method elements.
-   */
-  @deprecated // Use MethodElement.EMPTY_LIST
-  static const List<MethodElement> EMPTY_ARRAY = const <MethodElement>[];
-
-  /**
-   * Initialize a newly created method element to have the given [name] at the
-   * given [offset].
-   */
-  MethodElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created method element to have the given [name].
-   */
-  MethodElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Set whether this method is abstract.
-   */
-  void set abstract(bool isAbstract) {
-    setModifier(Modifier.ABSTRACT, isAbstract);
-  }
-
-  @override
-  String get displayName {
-    String displayName = super.displayName;
-    if ("unary-" == displayName) {
-      return "-";
-    }
-    return displayName;
-  }
-
-  @override
-  ClassElement get enclosingElement => super.enclosingElement as ClassElement;
-
-  @override
-  bool get isOperator {
-    String name = displayName;
-    if (name.isEmpty) {
-      return false;
-    }
-    int first = name.codeUnitAt(0);
-    return !((0x61 <= first && first <= 0x7A) ||
-        (0x41 <= first && first <= 0x5A) ||
-        first == 0x5F ||
-        first == 0x24);
-  }
-
-  @override
-  bool get isStatic => hasModifier(Modifier.STATIC);
-
-  @override
-  ElementKind get kind => ElementKind.METHOD;
-
-  @override
-  String get name {
-    String name = super.name;
-    if (isOperator && name == "-") {
-      if (parameters.length == 0) {
-        return "unary-";
-      }
-    }
-    return super.name;
-  }
-
-  /**
-   * Set whether this method is static.
-   */
-  void set static(bool isStatic) {
-    setModifier(Modifier.STATIC, isStatic);
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitMethodElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write(displayName);
-    super.appendTo(buffer);
-  }
-
-  @override
-  MethodDeclaration computeNode() =>
-      getNodeMatching((node) => node is MethodDeclaration);
-}
-
-/**
- * A method element defined in a parameterized type where the values of the type
- * parameters are known.
- */
-class MethodMember extends ExecutableMember implements MethodElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  MethodMember(MethodElement baseElement, InterfaceType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  MethodElement get baseElement => super.baseElement as MethodElement;
-
-  @override
-  ClassElement get enclosingElement => baseElement.enclosingElement;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitMethodElement(this);
-
-  @override
-  MethodDeclaration computeNode() => baseElement.computeNode();
-
-  @override
-  String toString() {
-    MethodElement baseElement = this.baseElement;
-    List<ParameterElement> parameters = this.parameters;
-    FunctionType type = this.type;
-    StringBuffer buffer = new StringBuffer();
-    buffer.write(baseElement.enclosingElement.displayName);
-    buffer.write(".");
-    buffer.write(baseElement.displayName);
-    buffer.write("(");
-    int parameterCount = parameters.length;
-    for (int i = 0; i < parameterCount; i++) {
-      if (i > 0) {
-        buffer.write(", ");
-      }
-      buffer.write(parameters[i]);
-    }
-    buffer.write(")");
-    if (type != null) {
-      buffer.write(Element.RIGHT_ARROW);
-      buffer.write(type.returnType);
-    }
-    return buffer.toString();
-  }
-
-  /**
-   * If the given [method]'s type is different when any type parameters from the
-   * defining type's declaration are replaced with the actual type arguments
-   * from the [definingType], create a method member representing the given
-   * method. Return the member that was created, or the base method if no member
-   * was created.
-   */
-  static MethodElement from(MethodElement method, InterfaceType definingType) {
-    if (method == null || definingType.typeArguments.length == 0) {
-      return method;
-    }
-    FunctionType baseType = method.type;
-    List<DartType> argumentTypes = definingType.typeArguments;
-    List<DartType> parameterTypes = definingType.element.type.typeArguments;
-    FunctionType substitutedType =
-        baseType.substitute2(argumentTypes, parameterTypes);
-    if (baseType == substitutedType) {
-      return method;
-    }
-    // TODO(brianwilkerson) Consider caching the substituted type in the
-    // instance. It would use more memory but speed up some operations.
-    // We need to see how often the type is being re-computed.
-    return new MethodMember(method, definingType);
-  }
-}
-
-/**
- * The enumeration `Modifier` defines constants for all of the modifiers defined
- * by the Dart language and for a few additional flags that are useful.
- */
-class Modifier extends Enum<Modifier> {
-  /**
-   * Indicates that the modifier 'abstract' was applied to the element.
-   */
-  static const Modifier ABSTRACT = const Modifier('ABSTRACT', 0);
-
-  /**
-   * Indicates that an executable element has a body marked as being
-   * asynchronous.
-   */
-  static const Modifier ASYNCHRONOUS = const Modifier('ASYNCHRONOUS', 1);
-
-  /**
-   * Indicates that the modifier 'const' was applied to the element.
-   */
-  static const Modifier CONST = const Modifier('CONST', 2);
-
-  /**
-   * Indicates that the import element represents a deferred library.
-   */
-  static const Modifier DEFERRED = const Modifier('DEFERRED', 3);
-
-  /**
-   * Indicates that a class element was defined by an enum declaration.
-   */
-  static const Modifier ENUM = const Modifier('ENUM', 4);
-
-  /**
-   * Indicates that a class element was defined by an enum declaration.
-   */
-  static const Modifier EXTERNAL = const Modifier('EXTERNAL', 5);
-
-  /**
-   * Indicates that the modifier 'factory' was applied to the element.
-   */
-  static const Modifier FACTORY = const Modifier('FACTORY', 6);
-
-  /**
-   * Indicates that the modifier 'final' was applied to the element.
-   */
-  static const Modifier FINAL = const Modifier('FINAL', 7);
-
-  /**
-   * Indicates that an executable element has a body marked as being a
-   * generator.
-   */
-  static const Modifier GENERATOR = const Modifier('GENERATOR', 8);
-
-  /**
-   * Indicates that the pseudo-modifier 'get' was applied to the element.
-   */
-  static const Modifier GETTER = const Modifier('GETTER', 9);
-
-  /**
-   * A flag used for libraries indicating that the defining compilation unit
-   * contains at least one import directive whose URI uses the "dart-ext"
-   * scheme.
-   */
-  static const Modifier HAS_EXT_URI = const Modifier('HAS_EXT_URI', 10);
-
-  /**
-   * Indicates that a class can validly be used as a mixin.
-   */
-  static const Modifier MIXIN = const Modifier('MIXIN', 11);
-
-  /**
-   * Indicates that a class is a mixin application.
-   */
-  static const Modifier MIXIN_APPLICATION =
-      const Modifier('MIXIN_APPLICATION', 12);
-
-  /**
-   * Indicates that the value of a parameter or local variable might be mutated
-   * within the context.
-   */
-  static const Modifier POTENTIALLY_MUTATED_IN_CONTEXT =
-      const Modifier('POTENTIALLY_MUTATED_IN_CONTEXT', 13);
-
-  /**
-   * Indicates that the value of a parameter or local variable might be mutated
-   * within the scope.
-   */
-  static const Modifier POTENTIALLY_MUTATED_IN_SCOPE =
-      const Modifier('POTENTIALLY_MUTATED_IN_SCOPE', 14);
-
-  /**
-   * Indicates that a class contains an explicit reference to 'super'.
-   */
-  static const Modifier REFERENCES_SUPER =
-      const Modifier('REFERENCES_SUPER', 15);
-
-  /**
-   * Indicates that the pseudo-modifier 'set' was applied to the element.
-   */
-  static const Modifier SETTER = const Modifier('SETTER', 16);
-
-  /**
-   * Indicates that the modifier 'static' was applied to the element.
-   */
-  static const Modifier STATIC = const Modifier('STATIC', 17);
-
-  /**
-   * Indicates that the element does not appear in the source code but was
-   * implicitly created. For example, if a class does not define any
-   * constructors, an implicit zero-argument constructor will be created and it
-   * will be marked as being synthetic.
-   */
-  static const Modifier SYNTHETIC = const Modifier('SYNTHETIC', 18);
-
-  static const List<Modifier> values = const [
-    ABSTRACT,
-    ASYNCHRONOUS,
-    CONST,
-    DEFERRED,
-    ENUM,
-    EXTERNAL,
-    FACTORY,
-    FINAL,
-    GENERATOR,
-    GETTER,
-    HAS_EXT_URI,
-    MIXIN,
-    MIXIN_APPLICATION,
-    POTENTIALLY_MUTATED_IN_CONTEXT,
-    POTENTIALLY_MUTATED_IN_SCOPE,
-    REFERENCES_SUPER,
-    SETTER,
-    STATIC,
-    SYNTHETIC
-  ];
-
-  const Modifier(String name, int ordinal) : super(name, ordinal);
-}
-
-/**
- * A pseudo-element that represents multiple elements defined within a single
- * scope that have the same name. This situation is not allowed by the language,
- * so objects implementing this interface always represent an error. As a
- * result, most of the normal operations on elements do not make sense and will
- * return useless results.
- */
-abstract class MultiplyDefinedElement implements Element {
-  /**
-   * Return a list containing all of the elements that were defined within the
-   * scope to have the same name.
-   */
-  List<Element> get conflictingElements;
-
-  /**
-   * Return the type of this element as the dynamic type.
-   */
-  DartType get type;
-}
-
-/**
- * A concrete implementation of a [MultiplyDefinedElement].
- */
-class MultiplyDefinedElementImpl implements MultiplyDefinedElement {
-  /**
-   * The unique integer identifier of this element.
-   */
-  final int id = ElementImpl._NEXT_ID++;
-
-  /**
-   * The analysis context in which the multiply defined elements are defined.
-   */
-  final AnalysisContext context;
-
-  /**
-   * The name of the conflicting elements.
-   */
-  String _name;
-
-  /**
-   * A list containing all of the elements that conflict.
-   */
-  final List<Element> conflictingElements;
-
-  /**
-   * Initialize a newly created element in the given [context] to represent a
-   * list of [conflictingElements].
-   */
-  MultiplyDefinedElementImpl(this.context, this.conflictingElements) {
-    _name = conflictingElements[0].name;
-  }
-
-  @override
-  String get displayName => _name;
-
-  @override
-  Element get enclosingElement => null;
-
-  @override
-  bool get isDeprecated => false;
-
-  @override
-  bool get isOverride => false;
-
-  @override
-  bool get isPrivate {
-    String name = displayName;
-    if (name == null) {
-      return false;
-    }
-    return Identifier.isPrivateName(name);
-  }
-
-  @override
-  bool get isPublic => !isPrivate;
-
-  @override
-  bool get isSynthetic => true;
-
-  @override
-  ElementKind get kind => ElementKind.ERROR;
-
-  @override
-  LibraryElement get library => null;
-
-  @override
-  ElementLocation get location => null;
-
-  @override
-  List<ElementAnnotation> get metadata => ElementAnnotation.EMPTY_LIST;
-
-  @override
-  String get name => _name;
-
-  @override
-  int get nameOffset => -1;
-
-  @deprecated
-  @override
-  AstNode get node => null;
-
-  @override
-  Source get source => null;
-
-  @override
-  DartType get type => DynamicTypeImpl.instance;
-
-  @override
-  CompilationUnit get unit => null;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitMultiplyDefinedElement(this);
-
-  @override
-  String computeDocumentationComment() => null;
-
-  @override
-  AstNode computeNode() => null;
-
-  @override
-  Element getAncestor(Predicate<Element> predicate) => null;
-
-  @override
-  String getExtendedDisplayName(String shortName) {
-    if (shortName != null) {
-      return shortName;
-    }
-    return displayName;
-  }
-
-  @override
-  bool isAccessibleIn(LibraryElement library) {
-    for (Element element in conflictingElements) {
-      if (element.isAccessibleIn(library)) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  @override
-  String toString() {
-    StringBuffer buffer = new StringBuffer();
-    buffer.write("[");
-    int count = conflictingElements.length;
-    for (int i = 0; i < count; i++) {
-      if (i > 0) {
-        buffer.write(", ");
-      }
-      (conflictingElements[i] as ElementImpl).appendTo(buffer);
-    }
-    buffer.write("]");
-    return buffer.toString();
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    // There are no children to visit
-  }
-
-  /**
-   * Return an element in the given [context] that represents the fact that the
-   * [firstElement] and [secondElement] conflict. (If the elements are the same,
-   * then one of the two will be returned directly.)
-   */
-  static Element fromElements(
-      AnalysisContext context, Element firstElement, Element secondElement) {
-    List<Element> conflictingElements =
-        _computeConflictingElements(firstElement, secondElement);
-    int length = conflictingElements.length;
-    if (length == 0) {
-      return null;
-    } else if (length == 1) {
-      return conflictingElements[0];
-    }
-    return new MultiplyDefinedElementImpl(context, conflictingElements);
-  }
-
-  /**
-   * Add the given [element] to the list of [elements]. If the element is a
-   * multiply-defined element, add all of the conflicting elements that it
-   * represents.
-   */
-  static void _add(HashSet<Element> elements, Element element) {
-    if (element is MultiplyDefinedElementImpl) {
-      for (Element conflictingElement in element.conflictingElements) {
-        elements.add(conflictingElement);
-      }
-    } else {
-      elements.add(element);
-    }
-  }
-
-  /**
-   * Use the given elements to construct a list of conflicting elements. If
-   * either the [firstElement] or [secondElement] are multiply-defined elements
-   * then the conflicting elements they represent will be included in the array.
-   * Otherwise, the element itself will be included.
-   */
-  static List<Element> _computeConflictingElements(
-      Element firstElement, Element secondElement) {
-    HashSet<Element> elements = new HashSet<Element>();
-    _add(elements, firstElement);
-    _add(elements, secondElement);
-    return new List.from(elements);
-  }
-}
-
-/**
- * An [ExecutableElement], with the additional information of a list of
- * [ExecutableElement]s from which this element was composed.
- */
-abstract class MultiplyInheritedExecutableElement implements ExecutableElement {
-  /**
-   * Return a list containing all of the executable elements defined within this
-   * executable element.
-   */
-  List<ExecutableElement> get inheritedElements;
-}
-
-/**
- * A [MethodElementImpl], with the additional information of a list of
- * [ExecutableElement]s from which this element was composed.
- */
-class MultiplyInheritedMethodElementImpl extends MethodElementImpl
-    implements MultiplyInheritedExecutableElement {
-  /**
-   * A list the array of executable elements that were used to compose this
-   * element.
-   */
-  List<ExecutableElement> _elements = MethodElement.EMPTY_LIST;
-
-  MultiplyInheritedMethodElementImpl(Identifier name) : super.forNode(name) {
-    synthetic = true;
-  }
-
-  @override
-  List<ExecutableElement> get inheritedElements => _elements;
-
-  void set inheritedElements(List<ExecutableElement> elements) {
-    this._elements = elements;
-  }
-}
-
-/**
- * A [PropertyAccessorElementImpl], with the additional information of a list of
- * [ExecutableElement]s from which this element was composed.
- */
-class MultiplyInheritedPropertyAccessorElementImpl
-    extends PropertyAccessorElementImpl
-    implements MultiplyInheritedExecutableElement {
-  /**
-   * A list the array of executable elements that were used to compose this
-   * element.
-   */
-  List<ExecutableElement> _elements = PropertyAccessorElement.EMPTY_LIST;
-
-  MultiplyInheritedPropertyAccessorElementImpl(Identifier name)
-      : super.forNode(name) {
-    synthetic = true;
-  }
-
-  @override
-  List<ExecutableElement> get inheritedElements => _elements;
-
-  void set inheritedElements(List<ExecutableElement> elements) {
-    this._elements = elements;
-  }
-}
-
-/**
- * An object that controls how namespaces are combined.
- */
-abstract class NamespaceCombinator {
-  /**
-   * An empty list of namespace combinators.
-   */
-  @deprecated // Use NamespaceCombinator.EMPTY_LIST
-  static const List<NamespaceCombinator> EMPTY_ARRAY =
-      const <NamespaceCombinator>[];
-
-  /**
-   * An empty list of namespace combinators.
-   */
-  static const List<NamespaceCombinator> EMPTY_LIST =
-      const <NamespaceCombinator>[];
-}
-
-/**
- * A parameter defined within an executable element.
- */
-abstract class ParameterElement
-    implements LocalElement, VariableElement, ConstantEvaluationTarget {
-  /**
-   * An empty list of parameter elements.
-   */
-  static const List<ParameterElement> EMPTY_LIST = const <ParameterElement>[];
-
-  /**
-   * Return the Dart code of the default value, or `null` if no default value.
-   */
-  String get defaultValueCode;
-
-  /**
-   * Return `true` if this parameter is an initializing formal parameter.
-   */
-  bool get isInitializingFormal;
-
-  /**
-   * Return the kind of this parameter.
-   */
-  ParameterKind get parameterKind;
-
-  /**
-   * Return a list containing all of the parameters defined by this parameter.
-   * A parameter will only define other parameters if it is a function typed
-   * parameter.
-   */
-  List<ParameterElement> get parameters;
-
-  /**
-   * Return a list containing all of the type parameters defined by this
-   * parameter. A parameter will only define other parameters if it is a
-   * function typed parameter.
-   */
-  List<TypeParameterElement> get typeParameters;
-
-  @override
-  FormalParameter computeNode();
-}
-
-/**
- * A concrete implementation of a [ParameterElement].
- */
-class ParameterElementImpl extends VariableElementImpl
-    with PotentiallyConstVariableElement implements ParameterElement {
-  /**
-   * An empty list of parameter elements.
-   */
-  @deprecated // Use ParameterElement.EMPTY_LIST
-  static const List<ParameterElement> EMPTY_ARRAY = const <ParameterElement>[];
-
-  /**
-   * A list containing all of the parameters defined by this parameter element.
-   * There will only be parameters if this parameter is a function typed
-   * parameter.
-   */
-  List<ParameterElement> _parameters = ParameterElement.EMPTY_LIST;
-
-  /**
-   * A list containing all of the type parameters defined for this parameter
-   * element. There will only be parameters if this parameter is a function
-   * typed parameter.
-   */
-  List<TypeParameterElement> _typeParameters = TypeParameterElement.EMPTY_LIST;
-
-  /**
-   * The kind of this parameter.
-   */
-  ParameterKind parameterKind;
-
-  /**
-   * The Dart code of the default value.
-   */
-  String _defaultValueCode;
-
-  /**
-   * The offset to the beginning of the visible range for this element.
-   */
-  int _visibleRangeOffset = 0;
-
-  /**
-   * The length of the visible range for this element, or `-1` if this element
-   * does not have a visible range.
-   */
-  int _visibleRangeLength = -1;
-
-  /**
-   * Initialize a newly created parameter element to have the given [name] and
-   * [offset].
-   */
-  ParameterElementImpl(String name, int nameOffset) : super(name, nameOffset);
-
-  /**
-   * Initialize a newly created parameter element to have the given [name].
-   */
-  ParameterElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  String get defaultValueCode => _defaultValueCode;
-
-  /**
-   * Set Dart code of the default value.
-   */
-  void set defaultValueCode(String defaultValueCode) {
-    this._defaultValueCode = StringUtilities.intern(defaultValueCode);
-  }
-
-  @override
-  bool get isInitializingFormal => false;
-
-  @override
-  bool get isPotentiallyMutatedInClosure =>
-      hasModifier(Modifier.POTENTIALLY_MUTATED_IN_CONTEXT);
-
-  @override
-  bool get isPotentiallyMutatedInScope =>
-      hasModifier(Modifier.POTENTIALLY_MUTATED_IN_SCOPE);
-
-  @override
-  ElementKind get kind => ElementKind.PARAMETER;
-
-  @override
-  List<ParameterElement> get parameters => _parameters;
-
-  /**
-   * Set the parameters defined by this executable element to the given
-   * [parameters].
-   */
-  void set parameters(List<ParameterElement> parameters) {
-    for (ParameterElement parameter in parameters) {
-      (parameter as ParameterElementImpl).enclosingElement = this;
-    }
-    this._parameters = parameters;
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters => _typeParameters;
-
-  /**
-   * Set the type parameters defined by this parameter element to the given
-   * [typeParameters].
-   */
-  void set typeParameters(List<TypeParameterElement> typeParameters) {
-    for (TypeParameterElement parameter in typeParameters) {
-      (parameter as TypeParameterElementImpl).enclosingElement = this;
-    }
-    this._typeParameters = typeParameters;
-  }
-
-  @override
-  SourceRange get visibleRange {
-    if (_visibleRangeLength < 0) {
-      return null;
-    }
-    return new SourceRange(_visibleRangeOffset, _visibleRangeLength);
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitParameterElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    String left = "";
-    String right = "";
-    while (true) {
-      if (parameterKind == ParameterKind.NAMED) {
-        left = "{";
-        right = "}";
-      } else if (parameterKind == ParameterKind.POSITIONAL) {
-        left = "[";
-        right = "]";
-      } else if (parameterKind == ParameterKind.REQUIRED) {}
-      break;
-    }
-    buffer.write(left);
-    appendToWithoutDelimiters(buffer);
-    buffer.write(right);
-  }
-
-  /**
-   * Append the type and name of this parameter to the given [buffer].
-   */
-  void appendToWithoutDelimiters(StringBuffer buffer) {
-    buffer.write(type);
-    buffer.write(" ");
-    buffer.write(displayName);
-    if (_defaultValueCode != null) {
-      if (parameterKind == ParameterKind.NAMED) {
-        buffer.write(": ");
-      }
-      if (parameterKind == ParameterKind.POSITIONAL) {
-        buffer.write(" = ");
-      }
-      buffer.write(_defaultValueCode);
-    }
-  }
-
-  @override
-  FormalParameter computeNode() =>
-      getNodeMatching((node) => node is FormalParameter);
-
-  @override
-  ElementImpl getChild(String identifier) {
-    for (ParameterElement parameter in _parameters) {
-      if ((parameter as ParameterElementImpl).identifier == identifier) {
-        return parameter as ParameterElementImpl;
-      }
-    }
-    return null;
-  }
-
-  /**
-   * Specifies that this variable is potentially mutated somewhere in closure.
-   */
-  void markPotentiallyMutatedInClosure() {
-    setModifier(Modifier.POTENTIALLY_MUTATED_IN_CONTEXT, true);
-  }
-
-  /**
-   * Specifies that this variable is potentially mutated somewhere in its scope.
-   */
-  void markPotentiallyMutatedInScope() {
-    setModifier(Modifier.POTENTIALLY_MUTATED_IN_SCOPE, true);
-  }
-
-  /**
-   * Set the visible range for this element to the range starting at the given
-   * [offset] with the given [length].
-   */
-  void setVisibleRange(int offset, int length) {
-    _visibleRangeOffset = offset;
-    _visibleRangeLength = length;
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(_parameters, visitor);
-  }
-}
-
-/**
- * A type with type parameters, such as a class or function type alias.
- */
-abstract class ParameterizedType implements DartType {
-  /**
-   * Return a list containing the actual types of the type arguments. If this
-   * type's element does not have type parameters, then the array should be
-   * empty (although it is possible for type arguments to be erroneously
-   * declared). If the element has type parameters and the actual type does not
-   * explicitly include argument values, then the type "dynamic" will be
-   * automatically provided.
-   */
-  List<DartType> get typeArguments;
-
-  /**
-   * Return a list containing all of the type parameters declared for this type.
-   */
-  List<TypeParameterElement> get typeParameters;
-}
-
-/**
- * A parameter element defined in a parameterized type where the values of the
- * type parameters are known.
- */
-class ParameterMember extends VariableMember implements ParameterElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  ParameterMember(ParameterElement baseElement, ParameterizedType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  ParameterElement get baseElement => super.baseElement as ParameterElement;
-
-  @override
-  String get defaultValueCode => baseElement.defaultValueCode;
-
-  @override
-  Element get enclosingElement => baseElement.enclosingElement;
-
-  @override
-  bool get isInitializingFormal => baseElement.isInitializingFormal;
-
-  @override
-  ParameterKind get parameterKind => baseElement.parameterKind;
-
-  @override
-  List<ParameterElement> get parameters {
-    List<ParameterElement> baseParameters = baseElement.parameters;
-    int parameterCount = baseParameters.length;
-    if (parameterCount == 0) {
-      return baseParameters;
-    }
-    List<ParameterElement> parameterizedParameters =
-        new List<ParameterElement>(parameterCount);
-    for (int i = 0; i < parameterCount; i++) {
-      parameterizedParameters[i] =
-          ParameterMember.from(baseParameters[i], definingType);
-    }
-    return parameterizedParameters;
-  }
-
-  @override
-  List<TypeParameterElement> get typeParameters => baseElement.typeParameters;
-
-  @override
-  SourceRange get visibleRange => baseElement.visibleRange;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitParameterElement(this);
-
-  @override
-  FormalParameter computeNode() => baseElement.computeNode();
-
-  @override
-  Element getAncestor(Predicate<Element> predicate) {
-    Element element = baseElement.getAncestor(predicate);
-    ParameterizedType definingType = this.definingType;
-    if (definingType is InterfaceType) {
-      InterfaceType definingInterfaceType = definingType;
-      if (element is ConstructorElement) {
-        return ConstructorMember.from(element, definingInterfaceType);
-      } else if (element is MethodElement) {
-        return MethodMember.from(element, definingInterfaceType);
-      } else if (element is PropertyAccessorElement) {
-        return PropertyAccessorMember.from(element, definingInterfaceType);
-      }
-    }
-    return element;
-  }
-
-  @override
-  String toString() {
-    ParameterElement baseElement = this.baseElement;
-    String left = "";
-    String right = "";
-    while (true) {
-      if (baseElement.parameterKind == ParameterKind.NAMED) {
-        left = "{";
-        right = "}";
-      } else if (baseElement.parameterKind == ParameterKind.POSITIONAL) {
-        left = "[";
-        right = "]";
-      } else if (baseElement.parameterKind == ParameterKind.REQUIRED) {}
-      break;
-    }
-    return '$left$type ${baseElement.displayName}$right';
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChildren(parameters, visitor);
-  }
-
-  /**
-   * If the given [parameter]'s type is different when any type parameters from
-   * the defining type's declaration are replaced with the actual type
-   * arguments from the [definingType], create a parameter member representing
-   * the given parameter. Return the member that was created, or the base
-   * parameter if no member was created.
-   */
-  static ParameterElement from(
-      ParameterElement parameter, ParameterizedType definingType) {
-    if (parameter == null || definingType.typeArguments.length == 0) {
-      return parameter;
-    }
-    // Check if parameter type depends on defining type type arguments.
-    // It is possible that we did not resolve field formal parameter yet,
-    // so skip this check for it.
-    bool isFieldFormal = parameter is FieldFormalParameterElement;
-    if (!isFieldFormal) {
-      DartType baseType = parameter.type;
-      List<DartType> argumentTypes = definingType.typeArguments;
-      List<DartType> parameterTypes =
-          TypeParameterTypeImpl.getTypes(definingType.typeParameters);
-      DartType substitutedType =
-          baseType.substitute2(argumentTypes, parameterTypes);
-      if (baseType == substitutedType) {
-        return parameter;
-      }
-    }
-    // TODO(brianwilkerson) Consider caching the substituted type in the
-    // instance. It would use more memory but speed up some operations.
-    // We need to see how often the type is being re-computed.
-    if (isFieldFormal) {
-      return new FieldFormalParameterMember(
-          parameter as FieldFormalParameterElement, definingType);
-    }
-    return new ParameterMember(parameter, definingType);
-  }
-}
-
-/**
- * Interface used by elements that might represent constant variables.
- *
- * This class may be used as a mixin in the case where [constInitializer] is
- * known to return null.
- *
- * This class is not intended to be part of the public API for analyzer.
- */
-abstract class PotentiallyConstVariableElement
-    implements VariableElementImpl, ConstantEvaluationTarget {
-  /**
-   * If this element represents a constant variable, and it has an initializer,
-   * a copy of the initializer for the constant.  Otherwise `null`.
-   *
-   * Note that in correct Dart code, all constant variables must have
-   * initializers.  However, analyzer also needs to handle incorrect Dart code,
-   * in which case there might be some constant variables that lack
-   * initializers.
-   */
-  Expression get constantInitializer => null;
-}
-
-/**
- * A prefix used to import one or more libraries into another library.
- */
-abstract class PrefixElement implements Element {
-  /**
-   * An empty list of prefix elements.
-   */
-  static const List<PrefixElement> EMPTY_LIST = const <PrefixElement>[];
-
-  /**
-   * Return the library into which other libraries are imported using this
-   * prefix.
-   */
-  @override
-  LibraryElement get enclosingElement;
-
-  /**
-   * Return a list containing all of the libraries that are imported using this
-   * prefix.
-   */
-  List<LibraryElement> get importedLibraries;
-}
-
-/**
- * A concrete implementation of a [PrefixElement].
- */
-class PrefixElementImpl extends ElementImpl implements PrefixElement {
-  /**
-   * An empty list of prefix elements.
-   */
-  @deprecated // Use PrefixElement.EMPTY_LIST
-  static const List<PrefixElement> EMPTY_ARRAY = const <PrefixElement>[];
-
-  /**
-   * A list containing all of the libraries that are imported using this prefix.
-   */
-  List<LibraryElement> _importedLibraries = LibraryElement.EMPTY_LIST;
-
-  /**
-   * Initialize a newly created method element to have the given [name] and
-   * [offset].
-   */
-  PrefixElementImpl(String name, int nameOffset) : super(name, nameOffset);
-
-  /**
-   * Initialize a newly created prefix element to have the given [name].
-   */
-  PrefixElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  LibraryElement get enclosingElement =>
-      super.enclosingElement as LibraryElement;
-
-  @override
-  String get identifier => "_${super.identifier}";
-
-  @override
-  List<LibraryElement> get importedLibraries => _importedLibraries;
-
-  /**
-   * Set the libraries that are imported using this prefix to the given
-   * [libraries].
-   */
-  void set importedLibraries(List<LibraryElement> libraries) {
-    for (LibraryElement library in libraries) {
-      (library as LibraryElementImpl).enclosingElement = this;
-    }
-    _importedLibraries = libraries;
-  }
-
-  @override
-  ElementKind get kind => ElementKind.PREFIX;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitPrefixElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write("as ");
-    super.appendTo(buffer);
-  }
-}
-
-/**
- * A getter or a setter. Note that explicitly defined property accessors
- * implicitly define a synthetic field. Symmetrically, synthetic accessors are
- * implicitly created for explicitly defined fields. The following rules apply:
- *
- * * Every explicit field is represented by a non-synthetic [FieldElement].
- * * Every explicit field induces a getter and possibly a setter, both of which
- *   are represented by synthetic [PropertyAccessorElement]s.
- * * Every explicit getter or setter is represented by a non-synthetic
- *   [PropertyAccessorElement].
- * * Every explicit getter or setter (or pair thereof if they have the same
- *   name) induces a field that is represented by a synthetic [FieldElement].
- */
-abstract class PropertyAccessorElement implements ExecutableElement {
-  /**
-   * An empty list of property accessor elements.
-   */
-  static const List<PropertyAccessorElement> EMPTY_LIST =
-      const <PropertyAccessorElement>[];
-
-  /**
-   * Return the accessor representing the getter that corresponds to (has the
-   * same name as) this setter, or `null` if this accessor is not a setter or if
-   * there is no corresponding getter.
-   */
-  PropertyAccessorElement get correspondingGetter;
-
-  /**
-   * Return the accessor representing the setter that corresponds to (has the
-   * same name as) this getter, or `null` if this accessor is not a getter or if
-   * there is no corresponding setter.
-   */
-  PropertyAccessorElement get correspondingSetter;
-
-  /**
-   * Return `true` if this accessor represents a getter.
-   */
-  bool get isGetter;
-
-  /**
-   * Return `true` if this accessor represents a setter.
-   */
-  bool get isSetter;
-
-  /**
-   * Return the field or top-level variable associated with this accessor. If
-   * this accessor was explicitly defined (is not synthetic) then the variable
-   * associated with it will be synthetic.
-   */
-  PropertyInducingElement get variable;
-}
-
-/**
- * A concrete implementation of a [PropertyAccessorElement].
- */
-class PropertyAccessorElementImpl extends ExecutableElementImpl
-    implements PropertyAccessorElement {
-  /**
-   * An empty list of property accessor elements.
-   */
-  @deprecated // Use PropertyAccessorElement.EMPTY_LIST
-  static const List<PropertyAccessorElement> EMPTY_ARRAY =
-      const <PropertyAccessorElement>[];
-
-  /**
-   * The variable associated with this accessor.
-   */
-  PropertyInducingElement variable;
-
-  /**
-   * Initialize a newly created property accessor element to have the given
-   * [name].
-   */
-  PropertyAccessorElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Initialize a newly created synthetic property accessor element to be
-   * associated with the given [variable].
-   */
-  PropertyAccessorElementImpl.forVariable(PropertyInducingElementImpl variable)
-      : super(variable.name, variable.nameOffset) {
-    this.variable = variable;
-    static = variable.isStatic;
-    synthetic = true;
-  }
-
-  /**
-   * Set whether this accessor is abstract.
-   */
-  void set abstract(bool isAbstract) {
-    setModifier(Modifier.ABSTRACT, isAbstract);
-  }
-
-  @override
-  PropertyAccessorElement get correspondingGetter {
-    if (isGetter || variable == null) {
-      return null;
-    }
-    return variable.getter;
-  }
-
-  @override
-  PropertyAccessorElement get correspondingSetter {
-    if (isSetter || variable == null) {
-      return null;
-    }
-    return variable.setter;
-  }
-
-  /**
-   * Set whether this accessor is a getter.
-   */
-  void set getter(bool isGetter) {
-    setModifier(Modifier.GETTER, isGetter);
-  }
-
-  @override
-  int get hashCode => JenkinsSmiHash.hash2(super.hashCode, isGetter ? 1 : 2);
-
-  @override
-  String get identifier {
-    String name = displayName;
-    String suffix = isGetter ? "?" : "=";
-    return "$name$suffix";
-  }
-
-  @override
-  bool get isGetter => hasModifier(Modifier.GETTER);
-
-  @override
-  bool get isSetter => hasModifier(Modifier.SETTER);
-
-  @override
-  bool get isStatic => hasModifier(Modifier.STATIC);
-
-  @override
-  ElementKind get kind {
-    if (isGetter) {
-      return ElementKind.GETTER;
-    }
-    return ElementKind.SETTER;
-  }
-
-  @override
-  String get name {
-    if (isSetter) {
-      return "${super.name}=";
-    }
-    return super.name;
-  }
-
-  /**
-   * Set whether this accessor is a setter.
-   */
-  void set setter(bool isSetter) {
-    setModifier(Modifier.SETTER, isSetter);
-  }
-
-  /**
-   * Set whether this accessor is static.
-   */
-  void set static(bool isStatic) {
-    setModifier(Modifier.STATIC, isStatic);
-  }
-
-  @override
-  bool operator ==(Object object) => super == object &&
-      isGetter == (object as PropertyAccessorElement).isGetter;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitPropertyAccessorElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write(isGetter ? "get " : "set ");
-    buffer.write(variable.displayName);
-    super.appendTo(buffer);
-  }
-
-  @override
-  AstNode computeNode() {
-    if (isSynthetic) {
-      return null;
-    }
-    if (enclosingElement is ClassElement) {
-      return getNodeMatching((node) => node is MethodDeclaration);
-    }
-    if (enclosingElement is CompilationUnitElement) {
-      return getNodeMatching((node) => node is FunctionDeclaration);
-    }
-    return null;
-  }
-}
-
-/**
- * A property accessor element defined in a parameterized type where the values
- * of the type parameters are known.
- */
-class PropertyAccessorMember extends ExecutableMember
-    implements PropertyAccessorElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  PropertyAccessorMember(
-      PropertyAccessorElement baseElement, InterfaceType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  PropertyAccessorElement get baseElement =>
-      super.baseElement as PropertyAccessorElement;
-
-  @override
-  PropertyAccessorElement get correspondingGetter =>
-      from(baseElement.correspondingGetter, definingType);
-
-  @override
-  PropertyAccessorElement get correspondingSetter =>
-      from(baseElement.correspondingSetter, definingType);
-
-  @override
-  InterfaceType get definingType => super.definingType as InterfaceType;
-
-  @override
-  Element get enclosingElement => baseElement.enclosingElement;
-
-  @override
-  bool get isGetter => baseElement.isGetter;
-
-  @override
-  bool get isSetter => baseElement.isSetter;
-
-  @override
-  PropertyInducingElement get variable {
-    PropertyInducingElement variable = baseElement.variable;
-    if (variable is FieldElement) {
-      return FieldMember.from(variable, definingType);
-    }
-    return variable;
-  }
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitPropertyAccessorElement(this);
-
-  @override
-  String toString() {
-    PropertyAccessorElement baseElement = this.baseElement;
-    List<ParameterElement> parameters = this.parameters;
-    FunctionType type = this.type;
-    StringBuffer builder = new StringBuffer();
-    if (isGetter) {
-      builder.write("get ");
-    } else {
-      builder.write("set ");
-    }
-    builder.write(baseElement.enclosingElement.displayName);
-    builder.write(".");
-    builder.write(baseElement.displayName);
-    builder.write("(");
-    int parameterCount = parameters.length;
-    for (int i = 0; i < parameterCount; i++) {
-      if (i > 0) {
-        builder.write(", ");
-      }
-      builder.write(parameters[i]);
-    }
-    builder.write(")");
-    if (type != null) {
-      builder.write(Element.RIGHT_ARROW);
-      builder.write(type.returnType);
-    }
-    return builder.toString();
-  }
-
-  /**
-   * If the given [accessor]'s type is different when any type parameters from
-   * the defining type's declaration are replaced with the actual type
-   * arguments from the [definingType], create an accessor member representing
-   * the given accessor. Return the member that was created, or the base
-   * accessor if no member was created.
-   */
-  static PropertyAccessorElement from(
-      PropertyAccessorElement accessor, InterfaceType definingType) {
-    if (!_isChangedByTypeSubstitution(accessor, definingType)) {
-      return accessor;
-    }
-    // TODO(brianwilkerson) Consider caching the substituted type in the
-    // instance. It would use more memory but speed up some operations.
-    // We need to see how often the type is being re-computed.
-    return new PropertyAccessorMember(accessor, definingType);
-  }
-
-  /**
-   * Determine whether the given property [accessor]'s type is changed when type
-   * parameters from the defining type's declaration are replaced with the
-   * actual type arguments from the [definingType].
-   */
-  static bool _isChangedByTypeSubstitution(
-      PropertyAccessorElement accessor, InterfaceType definingType) {
-    List<DartType> argumentTypes = definingType.typeArguments;
-    if (accessor != null && argumentTypes.length != 0) {
-      FunctionType baseType = accessor.type;
-      if (baseType == null) {
-        AnalysisEngine.instance.logger.logInformation(
-            'Type of $accessor is null in PropertyAccessorMember._isChangedByTypeSubstitution');
-        return false;
-      }
-      List<DartType> parameterTypes = definingType.element.type.typeArguments;
-      FunctionType substitutedType =
-          baseType.substitute2(argumentTypes, parameterTypes);
-      if (baseType != substitutedType) {
-        return true;
-      }
-      // If this property accessor is based on a field, that field might have a
-      // propagated type. In which case we need to check whether the propagated
-      // type of the field needs substitution.
-      PropertyInducingElement field = accessor.variable;
-      if (!field.isSynthetic) {
-        DartType baseFieldType = field.propagatedType;
-        if (baseFieldType != null) {
-          DartType substitutedFieldType =
-              baseFieldType.substitute2(argumentTypes, parameterTypes);
-          if (baseFieldType != substitutedFieldType) {
-            return true;
-          }
-        }
-      }
-    }
-    return false;
-  }
-}
-
-/**
- * A variable that has an associated getter and possibly a setter. Note that
- * explicitly defined variables implicitly define a synthetic getter and that
- * non-`final` explicitly defined variables implicitly define a synthetic
- * setter. Symmetrically, synthetic fields are implicitly created for explicitly
- * defined getters and setters. The following rules apply:
- *
- * * Every explicit variable is represented by a non-synthetic
- *   [PropertyInducingElement].
- * * Every explicit variable induces a getter and possibly a setter, both of
- *   which are represented by synthetic [PropertyAccessorElement]s.
- * * Every explicit getter or setter is represented by a non-synthetic
- *   [PropertyAccessorElement].
- * * Every explicit getter or setter (or pair thereof if they have the same
- *   name) induces a variable that is represented by a synthetic
- *   [PropertyInducingElement].
- */
-abstract class PropertyInducingElement implements VariableElement {
-  /**
-   * An empty list of elements.
-   */
-  static const List<PropertyInducingElement> EMPTY_LIST =
-      const <PropertyInducingElement>[];
-
-  /**
-   * Return the getter associated with this variable. If this variable was
-   * explicitly defined (is not synthetic) then the getter associated with it
-   * will be synthetic.
-   */
-  PropertyAccessorElement get getter;
-
-  /**
-   * Return `true` if this element is a static element. A static element is an
-   * element that is not associated with a particular instance, but rather with
-   * an entire library or class.
-   */
-  bool get isStatic;
-
-  /**
-   * Return the propagated type of this variable, or `null` if type propagation
-   * has not been performed, for example because the variable is not final.
-   */
-  DartType get propagatedType;
-
-  /**
-   * Return the setter associated with this variable, or `null` if the variable
-   * is effectively `final` and therefore does not have a setter associated with
-   * it. (This can happen either because the variable is explicitly defined as
-   * being `final` or because the variable is induced by an explicit getter that
-   * does not have a corresponding setter.) If this variable was explicitly
-   * defined (is not synthetic) then the setter associated with it will be
-   * synthetic.
-   */
-  PropertyAccessorElement get setter;
-}
-
-/**
- * A concrete implementation of a [PropertyInducingElement].
- */
-abstract class PropertyInducingElementImpl extends VariableElementImpl
-    implements PropertyInducingElement {
-  /**
-   * An empty list of elements.
-   */
-  @deprecated // Use PropertyInducingElement.EMPTY_LIST
-  static const List<PropertyInducingElement> EMPTY_ARRAY =
-      const <PropertyInducingElement>[];
-
-  /**
-   * The getter associated with this element.
-   */
-  PropertyAccessorElement getter;
-
-  /**
-   * The setter associated with this element, or `null` if the element is
-   * effectively `final` and therefore does not have a setter associated with
-   * it.
-   */
-  PropertyAccessorElement setter;
-
-  /**
-   * The propagated type of this variable, or `null` if type propagation has not
-   * been performed.
-   */
-  DartType propagatedType;
-
-  /**
-   * Initialize a newly created synthetic element to have the given [name] and
-   * [offset].
-   */
-  PropertyInducingElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created element to have the given [name].
-   */
-  PropertyInducingElementImpl.forNode(Identifier name) : super.forNode(name);
-}
-
-/**
- * A visitor that will recursively visit all of the element in an element model.
- * For example, using an instance of this class to visit a
- * [CompilationUnitElement] will also cause all of the types in the compilation
- * unit to be visited.
- *
- * Subclasses that override a visit method must either invoke the overridden
- * visit method or must explicitly ask the visited element to visit its
- * children. Failure to do so will cause the children of the visited element to
- * not be visited.
- */
-class RecursiveElementVisitor<R> implements ElementVisitor<R> {
-  @override
-  R visitClassElement(ClassElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitCompilationUnitElement(CompilationUnitElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitConstructorElement(ConstructorElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  @deprecated
-  R visitEmbeddedHtmlScriptElement(EmbeddedHtmlScriptElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitExportElement(ExportElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  @deprecated
-  R visitExternalHtmlScriptElement(ExternalHtmlScriptElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitFieldElement(FieldElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitFieldFormalParameterElement(FieldFormalParameterElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitFunctionElement(FunctionElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitFunctionTypeAliasElement(FunctionTypeAliasElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  @deprecated
-  R visitHtmlElement(HtmlElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitImportElement(ImportElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitLabelElement(LabelElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitLibraryElement(LibraryElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitLocalVariableElement(LocalVariableElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitMethodElement(MethodElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitMultiplyDefinedElement(MultiplyDefinedElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitParameterElement(ParameterElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitPrefixElement(PrefixElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitPropertyAccessorElement(PropertyAccessorElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitTopLevelVariableElement(TopLevelVariableElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitTypeParameterElement(TypeParameterElement element) {
-    element.visitChildren(this);
-    return null;
-  }
-}
-
-/**
- * A combinator that cause some of the names in a namespace to be visible (and
- * the rest hidden) when being imported.
- */
-abstract class ShowElementCombinator implements NamespaceCombinator {
-  /**
-   * Return the offset of the character immediately following the last character
-   * of this node.
-   */
-  int get end;
-
-  /**
-   * Return the offset of the 'show' keyword of this element.
-   */
-  int get offset;
-
-  /**
-   * Return a list containing the names that are to be made visible in the
-   * importing library if they are defined in the imported library.
-   */
-  List<String> get shownNames;
-}
-
-/**
- * A concrete implementation of a [ShowElementCombinator].
- */
-class ShowElementCombinatorImpl implements ShowElementCombinator {
-  /**
-   * The names that are to be made visible in the importing library if they are
-   * defined in the imported library.
-   */
-  List<String> shownNames = StringUtilities.EMPTY_ARRAY;
-
-  /**
-   * The offset of the character immediately following the last character of
-   * this node.
-   */
-  int end = -1;
-
-  /**
-   * The offset of the 'show' keyword of this element.
-   */
-  int offset = 0;
-
-  @override
-  String toString() {
-    StringBuffer buffer = new StringBuffer();
-    buffer.write("show ");
-    int count = shownNames.length;
-    for (int i = 0; i < count; i++) {
-      if (i > 0) {
-        buffer.write(", ");
-      }
-      buffer.write(shownNames[i]);
-    }
-    return buffer.toString();
-  }
-}
-
-/**
- * A visitor that will do nothing when visiting an element. It is intended to be
- * a superclass for classes that use the visitor pattern primarily as a dispatch
- * mechanism (and hence don't need to recursively visit a whole structure) and
- * that only need to visit a small number of element types.
- */
-class SimpleElementVisitor<R> implements ElementVisitor<R> {
-  @override
-  R visitClassElement(ClassElement element) => null;
-
-  @override
-  R visitCompilationUnitElement(CompilationUnitElement element) => null;
-
-  @override
-  R visitConstructorElement(ConstructorElement element) => null;
-
-  @override
-  @deprecated
-  R visitEmbeddedHtmlScriptElement(EmbeddedHtmlScriptElement element) => null;
-
-  @override
-  R visitExportElement(ExportElement element) => null;
-
-  @override
-  @deprecated
-  R visitExternalHtmlScriptElement(ExternalHtmlScriptElement element) => null;
-
-  @override
-  R visitFieldElement(FieldElement element) => null;
-
-  @override
-  R visitFieldFormalParameterElement(FieldFormalParameterElement element) =>
-      null;
-
-  @override
-  R visitFunctionElement(FunctionElement element) => null;
-
-  @override
-  R visitFunctionTypeAliasElement(FunctionTypeAliasElement element) => null;
-
-  @override
-  @deprecated
-  R visitHtmlElement(HtmlElement element) => null;
-
-  @override
-  R visitImportElement(ImportElement element) => null;
-
-  @override
-  R visitLabelElement(LabelElement element) => null;
-
-  @override
-  R visitLibraryElement(LibraryElement element) => null;
-
-  @override
-  R visitLocalVariableElement(LocalVariableElement element) => null;
-
-  @override
-  R visitMethodElement(MethodElement element) => null;
-
-  @override
-  R visitMultiplyDefinedElement(MultiplyDefinedElement element) => null;
-
-  @override
-  R visitParameterElement(ParameterElement element) => null;
-
-  @override
-  R visitPrefixElement(PrefixElement element) => null;
-
-  @override
-  R visitPropertyAccessorElement(PropertyAccessorElement element) => null;
-
-  @override
-  R visitTopLevelVariableElement(TopLevelVariableElement element) => null;
-
-  @override
-  R visitTypeParameterElement(TypeParameterElement element) => null;
-}
-
-/**
- * A top-level variable.
- */
-abstract class TopLevelVariableElement implements PropertyInducingElement {
-  /**
-   * An empty list of top-level variable elements.
-   */
-  static const List<TopLevelVariableElement> EMPTY_LIST =
-      const <TopLevelVariableElement>[];
-
-  @override
-  VariableDeclaration computeNode();
-}
-
-/**
- * A concrete implementation of a [TopLevelVariableElement].
- */
-class TopLevelVariableElementImpl extends PropertyInducingElementImpl
-    with PotentiallyConstVariableElement implements TopLevelVariableElement {
-  /**
-   * An empty list of top-level variable elements.
-   */
-  @deprecated // Use TopLevelVariableElement.EMPTY_LIST
-  static const List<TopLevelVariableElement> EMPTY_ARRAY =
-      const <TopLevelVariableElement>[];
-
-  /**
-   * Initialize a newly created synthetic top-level variable element to have the
-   * given [name] and [offset].
-   */
-  TopLevelVariableElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created top-level variable element to have the given
-   * [name].
-   */
-  TopLevelVariableElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  bool get isStatic => true;
-
-  @override
-  ElementKind get kind => ElementKind.TOP_LEVEL_VARIABLE;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitTopLevelVariableElement(this);
-
-  @override
-  VariableDeclaration computeNode() =>
-      getNodeMatching((node) => node is VariableDeclaration);
-}
-
-/**
- * An element that defines a type.
- */
-abstract class TypeDefiningElement implements Element {
-  /**
-   * Return the type defined by this element.
-   */
-  DartType get type;
-}
-
-/**
- * The abstract class `TypeImpl` implements the behavior common to objects
- * representing the declared type of elements in the element model.
- */
-abstract class TypeImpl implements DartType {
-  /**
-   * An empty list of types.
-   */
-  @deprecated // Use DartType.EMPTY_LIST
-  static const List<DartType> EMPTY_ARRAY = const <DartType>[];
-
-  /**
-   * The element representing the declaration of this type, or `null` if the
-   * type has not, or cannot, be associated with an element.
-   */
-  final Element _element;
-
-  /**
-   * The name of this type, or `null` if the type does not have a name.
-   */
-  final String name;
-
-  /**
-   * Initialize a newly created type to be declared by the given [element] and
-   * to have the given [name].
-   */
-  TypeImpl(this._element, this.name);
-
-  @override
-  String get displayName => name;
-
-  @override
-  Element get element => _element;
-
-  @override
-  bool get isBottom => false;
-
-  @override
-  bool get isDartCoreFunction => false;
-
-  @override
-  bool get isDynamic => false;
-
-  @override
-  bool get isObject => false;
-
-  @override
-  bool get isUndefined => false;
-
-  @override
-  bool get isVoid => false;
-
-  /**
-   * Append a textual representation of this type to the given [buffer]. The set
-   * of [visitedTypes] is used to prevent infinite recusion.
-   */
-  void appendTo(StringBuffer buffer) {
-    if (name == null) {
-      buffer.write("<unnamed type>");
-    } else {
-      buffer.write(name);
-    }
-  }
-
-  @override
-  DartType getLeastUpperBound(DartType type) => null;
-
-  /**
-   * Return `true` if this type is assignable to the given [type] (written in
-   * the spec as "T <=> S", where T=[this] and S=[type]).
-   *
-   * The sets [thisExpansions] and [typeExpansions], if given, are the sets of
-   * function type aliases that have been expanded so far in the process of
-   * reaching [this] and [type], respectively.  These are used to avoid
-   * infinite regress when analyzing invalid code; since the language spec
-   * forbids a typedef from referring to itself directly or indirectly, we can
-   * use these as sets of function type aliases that don't need to be expanded.
-   */
-  @override
-  bool isAssignableTo(DartType type) {
-    // An interface type T may be assigned to a type S, written T <=> S, iff
-    // either T <: S or S <: T.
-    return isSubtypeOf(type) || (type as TypeImpl).isSubtypeOf(this);
-  }
-
-  /**
-   * Return `true` if this type is more specific than the given [type] (written
-   * in the spec as "T << S", where T=[this] and S=[type]).
-   *
-   * If [withDynamic] is `true`, then "dynamic" should be considered as a
-   * subtype of any type (as though "dynamic" had been replaced with bottom).
-   *
-   * The set [visitedElements], if given, is the set of classes and type
-   * parameters that have been visited so far while examining the class
-   * hierarchy of [this].  This is used to avoid infinite regress when
-   * analyzing invalid code; since the language spec forbids loops in the class
-   * hierarchy, we can use this as a set of classes that don't need to be
-   * examined when walking the class hierarchy.
-   */
-  @override
-  bool isMoreSpecificThan(DartType type,
-      [bool withDynamic = false, Set<Element> visitedElements]);
-
-  /**
-   * Return `true` if this type is a subtype of the given [type] (written in
-   * the spec as "T <: S", where T=[this] and S=[type]).
-   *
-   * The sets [thisExpansions] and [typeExpansions], if given, are the sets of
-   * function type aliases that have been expanded so far in the process of
-   * reaching [this] and [type], respectively.  These are used to avoid
-   * infinite regress when analyzing invalid code; since the language spec
-   * forbids a typedef from referring to itself directly or indirectly, we can
-   * use these as sets of function type aliases that don't need to be expanded.
-   */
-  @override
-  bool isSubtypeOf(DartType type) {
-    // For non-function types, T <: S iff [_|_/dynamic]T << S.
-    return isMoreSpecificThan(type, true);
-  }
-
-  @override
-  bool isSupertypeOf(DartType type) => type.isSubtypeOf(this);
-
-  /**
-   * Create a new [TypeImpl] that is identical to [this] except that when
-   * visiting type parameters, function parameter types, and function return
-   * types, function types listed in [prune] will not be expanded.  This is
-   * used to avoid creating infinite types in the presence of circular
-   * typedefs.
-   *
-   * If [prune] is null, then [this] is returned unchanged.
-   *
-   * Only legal to call on a [TypeImpl] that is not already subject to pruning.
-   */
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune);
-
-  /**
-   * Return the type resulting from substituting the given [argumentTypes] for
-   * the given [parameterTypes] in this type.
-   *
-   * In all classes derived from [TypeImpl], a new optional argument
-   * [prune] is added.  If specified, it is a list of function typdefs
-   * which should not be expanded.  This is used to avoid creating infinite
-   * types in response to self-referential typedefs.
-   */
-  @override
-  DartType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]);
-
-  @override
-  String toString() {
-    StringBuffer buffer = new StringBuffer();
-    appendTo(buffer);
-    return buffer.toString();
-  }
-
-  /**
-   * Return `true` if corresponding elements of the [first] and [second] lists
-   * of type arguments are all equal.
-   */
-  static bool equalArrays(List<DartType> first, List<DartType> second) {
-    if (first.length != second.length) {
-      return false;
-    }
-    for (int i = 0; i < first.length; i++) {
-      if (first[i] == null) {
-        AnalysisEngine.instance.logger
-            .logInformation('Found null type argument in TypeImpl.equalArrays');
-        return second[i] == null;
-      } else if (second[i] == null) {
-        AnalysisEngine.instance.logger
-            .logInformation('Found null type argument in TypeImpl.equalArrays');
-        return false;
-      }
-      if (first[i] != second[i]) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  /**
-   * Return a list containing the results of using the given [argumentTypes] and
-   * [parameterTypes] to perform a substitution on all of the given [types].
-   *
-   * If [prune] is specified, it is a list of function typdefs which should not
-   * be expanded.  This is used to avoid creating infinite types in response to
-   * self-referential typedefs.
-   */
-  static List<DartType> substitute(List<DartType> types,
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) {
-    int length = types.length;
-    if (length == 0) {
-      return types;
-    }
-    List<DartType> newTypes = new List<DartType>(length);
-    for (int i = 0; i < length; i++) {
-      newTypes[i] = (types[i] as TypeImpl).substitute2(
-          argumentTypes, parameterTypes, prune);
-    }
-    return newTypes;
-  }
-}
-
-/**
- * A type parameter.
- */
-abstract class TypeParameterElement implements Element {
-  /**
-   * An empty list of type parameter elements.
-   */
-  static const List<TypeParameterElement> EMPTY_LIST =
-      const <TypeParameterElement>[];
-
-  /**
-   * Return the type representing the bound associated with this parameter, or
-   * `null` if this parameter does not have an explicit bound.
-   */
-  DartType get bound;
-
-  /**
-   * Return the type defined by this type parameter.
-   */
-  TypeParameterType get type;
-}
-
-/**
- * A concrete implementation of a [TypeParameterElement].
- */
-class TypeParameterElementImpl extends ElementImpl
-    implements TypeParameterElement {
-  /**
-   * An empty list of type parameter elements.
-   */
-  @deprecated // Use TypeParameterElement.EMPTY_LIST
-  static const List<TypeParameterElement> EMPTY_ARRAY =
-      const <TypeParameterElement>[];
-
-  /**
-   * The type defined by this type parameter.
-   */
-  TypeParameterType type;
-
-  /**
-   * The type representing the bound associated with this parameter, or `null`
-   * if this parameter does not have an explicit bound.
-   */
-  DartType bound;
-
-  /**
-   * Initialize a newly created method element to have the given [name] and
-   * [offset].
-   */
-  TypeParameterElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created type parameter element to have the given [name].
-   */
-  TypeParameterElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  @override
-  ElementKind get kind => ElementKind.TYPE_PARAMETER;
-
-  @override
-  accept(ElementVisitor visitor) => visitor.visitTypeParameterElement(this);
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write(displayName);
-    if (bound != null) {
-      buffer.write(" extends ");
-      buffer.write(bound);
-    }
-  }
-}
-
-/**
- * The type introduced by a type parameter.
- */
-abstract class TypeParameterType implements DartType {
-  /**
-   * An empty list of type parameter types.
-   */
-  static const List<TypeParameterType> EMPTY_LIST = const <TypeParameterType>[];
-
-  @override
-  TypeParameterElement get element;
-}
-
-/**
- * A concrete implementation of a [TypeParameterType].
- */
-class TypeParameterTypeImpl extends TypeImpl implements TypeParameterType {
-  /**
-   * An empty list of type parameter types.
-   */
-  @deprecated // Use TypeParameterType.EMPTY_LIST
-  static const List<TypeParameterType> EMPTY_ARRAY =
-      const <TypeParameterType>[];
-
-  /**
-   * Initialize a newly created type parameter type to be declared by the given
-   * [element] and to have the given name.
-   */
-  TypeParameterTypeImpl(TypeParameterElement element)
-      : super(element, element.name);
-
-  @override
-  TypeParameterElement get element => super.element as TypeParameterElement;
-
-  @override
-  int get hashCode => element.hashCode;
-
-  @override
-  bool operator ==(Object object) =>
-      object is TypeParameterTypeImpl && (element == object.element);
-
-  @override
-  bool isMoreSpecificThan(DartType s,
-      [bool withDynamic = false, Set<Element> visitedElements]) {
-    //
-    // A type T is more specific than a type S, written T << S,
-    // if one of the following conditions is met:
-    //
-    // Reflexivity: T is S.
-    //
-    if (this == s) {
-      return true;
-    }
-    // S is dynamic.
-    //
-    if (s.isDynamic) {
-      return true;
-    }
-    //
-    // T is a type parameter and S is the upper bound of T.
-    //
-    TypeImpl bound = element.bound;
-    if (s == bound) {
-      return true;
-    }
-    //
-    // T is a type parameter and S is Object.
-    //
-    if (s.isObject) {
-      return true;
-    }
-    // We need upper bound to continue.
-    if (bound == null) {
-      return false;
-    }
-    //
-    // Transitivity: T << U and U << S.
-    //
-    // First check for infinite loops
-    if (element == null) {
-      return false;
-    }
-    if (visitedElements == null) {
-      visitedElements = new HashSet<Element>();
-    } else if (visitedElements.contains(element)) {
-      return false;
-    }
-    visitedElements.add(element);
-    try {
-      return bound.isMoreSpecificThan(s, withDynamic, visitedElements);
-    } finally {
-      visitedElements.remove(element);
-    }
-  }
-
-  @override
-  bool isSubtypeOf(DartType type) => isMoreSpecificThan(type, true);
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) => this;
-
-  @override
-  DartType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) {
-    int length = parameterTypes.length;
-    for (int i = 0; i < length; i++) {
-      if (parameterTypes[i] == this) {
-        return argumentTypes[i];
-      }
-    }
-    return this;
-  }
-
-  /**
-   * Return a list containing the type parameter types defined by the given
-   * array of type parameter elements ([typeParameters]).
-   */
-  static List<TypeParameterType> getTypes(
-      List<TypeParameterElement> typeParameters) {
-    int count = typeParameters.length;
-    if (count == 0) {
-      return TypeParameterType.EMPTY_LIST;
-    }
-    List<TypeParameterType> types = new List<TypeParameterType>(count);
-    for (int i = 0; i < count; i++) {
-      types[i] = typeParameters[i].type;
-    }
-    return types;
-  }
-}
-
-/**
- * A pseudo-elements that represents names that are undefined. This situation is
- * not allowed by the language, so objects implementing this interface always
- * represent an error. As a result, most of the normal operations on elements do
- * not make sense and will return useless results.
- */
-abstract class UndefinedElement implements Element {}
-
-/**
- * The unique instance of the class `UndefinedTypeImpl` implements the type of
- * typenames that couldn't be resolved.
- *
- * This class behaves like DynamicTypeImpl in almost every respect, to reduce
- * cascading errors.
- */
-class UndefinedTypeImpl extends TypeImpl {
-  /**
-   * The unique instance of this class.
-   */
-  static UndefinedTypeImpl _INSTANCE = new UndefinedTypeImpl._();
-
-  /**
-   * Return the unique instance of this class.
-   */
-  static UndefinedTypeImpl get instance => _INSTANCE;
-
-  /**
-   * Prevent the creation of instances of this class.
-   */
-  UndefinedTypeImpl._()
-      : super(DynamicElementImpl.instance, Keyword.DYNAMIC.syntax);
-
-  @override
-  int get hashCode => 1;
-
-  @override
-  bool get isDynamic => true;
-
-  @override
-  bool get isUndefined => true;
-
-  @override
-  bool operator ==(Object object) => identical(object, this);
-
-  @override
-  bool isMoreSpecificThan(DartType type,
-      [bool withDynamic = false, Set<Element> visitedElements]) {
-    // T is S
-    if (identical(this, type)) {
-      return true;
-    }
-    // else
-    return withDynamic;
-  }
-
-  @override
-  bool isSubtypeOf(DartType type) => true;
-
-  @override
-  bool isSupertypeOf(DartType type) => true;
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) => this;
-
-  @override
-  DartType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) {
-    int length = parameterTypes.length;
-    for (int i = 0; i < length; i++) {
-      if (parameterTypes[i] == this) {
-        return argumentTypes[i];
-      }
-    }
-    return this;
-  }
-}
-
-/**
- * An element included into a library using some URI.
- */
-abstract class UriReferencedElement implements Element {
-  /**
-   * Return the URI that is used to include this element into the enclosing
-   * library, or `null` if this is the defining compilation unit of a library.
-   */
-  String get uri;
-
-  /**
-   * Return the offset of the character immediately following the last character
-   * of this node's URI, or `-1` for synthetic import.
-   */
-  int get uriEnd;
-
-  /**
-   * Return the offset of the URI in the file, or `-1` if this element is
-   * synthetic.
-   */
-  int get uriOffset;
-}
-
-/**
- * A concrete implementation of a [UriReferencedElement].
- */
-abstract class UriReferencedElementImpl extends ElementImpl
-    implements UriReferencedElement {
-  /**
-   * The offset of the URI in the file, may be `-1` if synthetic.
-   */
-  int uriOffset = -1;
-
-  /**
-   * The offset of the character immediately following the last character of
-   * this node's URI, may be `-1` if synthetic.
-   */
-  int uriEnd = -1;
-
-  /**
-   * The URI that is specified by this directive.
-   */
-  String uri;
-
-  /**
-   * Initialize a newly created import element to heve the given [name] and
-   * [offset]. The offset may be `-1` if the element is synthetic.
-   */
-  UriReferencedElementImpl(String name, int offset) : super(name, offset);
-}
-
-/**
- * A variable. There are concrete subclasses for different kinds of variables.
- */
-abstract class VariableElement implements Element, ConstantEvaluationTarget {
-  /**
-   * An empty list of variable elements.
-   */
-  static const List<VariableElement> EMPTY_LIST = const <VariableElement>[];
-
-  /**
-   * Return a synthetic function representing this variable's initializer, or
-   * `null` if this variable does not have an initializer. The function will
-   * have no parameters. The return type of the function will be the
-   * compile-time type of the initialization expression.
-   */
-  FunctionElement get initializer;
-
-  /**
-   * Return `true` if this variable was declared with the 'const' modifier.
-   */
-  bool get isConst;
-
-  /**
-   * Return `true` if this variable was declared with the 'final' modifier.
-   * Variables that are declared with the 'const' modifier will return `false`
-   * even though they are implicitly final.
-   */
-  bool get isFinal;
-
-  /**
-   * Return `true` if this variable is potentially mutated somewhere in a
-   * closure. This information is only available for local variables (including
-   * parameters) and only after the compilation unit containing the variable has
-   * been resolved.
-   */
-  bool get isPotentiallyMutatedInClosure;
-
-  /**
-   * Return `true` if this variable is potentially mutated somewhere in its
-   * scope. This information is only available for local variables (including
-   * parameters) and only after the compilation unit containing the variable has
-   * been resolved.
-   */
-  bool get isPotentiallyMutatedInScope;
-
-  /**
-   * Return the declared type of this variable, or `null` if the variable did
-   * not have a declared type (such as if it was declared using the keyword
-   * 'var').
-   */
-  DartType get type;
-}
-
-/**
- * A concrete implementation of a [VariableElement].
- */
-abstract class VariableElementImpl extends ElementImpl
-    implements VariableElement {
-  /**
-   * An empty list of variable elements.
-   */
-  @deprecated // Use VariableElement.EMPTY_LIST
-  static const List<VariableElement> EMPTY_ARRAY = const <VariableElement>[];
-
-  /**
-   * The declared type of this variable.
-   */
-  DartType type;
-
-  /**
-   * A synthetic function representing this variable's initializer, or `null` if
-   * this variable does not have an initializer.
-   */
-  FunctionElement _initializer;
-
-  /**
-   * Initialize a newly created variable element to have the given [name] and
-   * [offset].
-   */
-  VariableElementImpl(String name, int offset) : super(name, offset);
-
-  /**
-   * Initialize a newly created variable element to have the given [name].
-   */
-  VariableElementImpl.forNode(Identifier name) : super.forNode(name);
-
-  /**
-   * Set whether this variable is const.
-   */
-  void set const3(bool isConst) {
-    setModifier(Modifier.CONST, isConst);
-  }
-
-  /**
-   * Return the result of evaluating this variable's initializer as a
-   * compile-time constant expression, or `null` if this variable is not a
-   * 'const' variable, if it does not have an initializer, or if the compilation
-   * unit containing the variable has not been resolved.
-   */
-  EvaluationResultImpl get evaluationResult => null;
-
-  /**
-   * Set the result of evaluating this variable's initializer as a compile-time
-   * constant expression to the given [result].
-   */
-  void set evaluationResult(EvaluationResultImpl result) {
-    throw new IllegalStateException(
-        "Invalid attempt to set a compile-time constant result");
-  }
-
-  /**
-   * Set whether this variable is final.
-   */
-  void set final2(bool isFinal) {
-    setModifier(Modifier.FINAL, isFinal);
-  }
-
-  @override
-  FunctionElement get initializer => _initializer;
-
-  /**
-   * Set the function representing this variable's initializer to the given
-   * [function].
-   */
-  void set initializer(FunctionElement function) {
-    if (function != null) {
-      (function as FunctionElementImpl).enclosingElement = this;
-    }
-    this._initializer = function;
-  }
-
-  @override
-  bool get isConst => hasModifier(Modifier.CONST);
-
-  @override
-  bool get isFinal => hasModifier(Modifier.FINAL);
-
-  @override
-  bool get isPotentiallyMutatedInClosure => false;
-
-  @override
-  bool get isPotentiallyMutatedInScope => false;
-
-  @override
-  void appendTo(StringBuffer buffer) {
-    buffer.write(type);
-    buffer.write(" ");
-    buffer.write(displayName);
-  }
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    super.visitChildren(visitor);
-    safelyVisitChild(_initializer, visitor);
-  }
-}
-
-/**
- * A variable element defined in a parameterized type where the values of the
- * type parameters are known.
- */
-abstract class VariableMember extends Member implements VariableElement {
-  /**
-   * Initialize a newly created element to represent a constructor, based on the
-   * [baseElement], defined by the [definingType].
-   */
-  VariableMember(VariableElement baseElement, ParameterizedType definingType)
-      : super(baseElement, definingType);
-
-  @override
-  VariableElement get baseElement => super.baseElement as VariableElement;
-
-  @override
-  FunctionElement get initializer {
-    //
-    // Elements within this element should have type parameters substituted,
-    // just like this element.
-    //
-    throw new UnsupportedOperationException();
-    //    return getBaseElement().getInitializer();
-  }
-
-  @override
-  bool get isConst => baseElement.isConst;
-
-  @override
-  bool get isFinal => baseElement.isFinal;
-
-  @override
-  bool get isPotentiallyMutatedInClosure =>
-      baseElement.isPotentiallyMutatedInClosure;
-
-  @override
-  bool get isPotentiallyMutatedInScope =>
-      baseElement.isPotentiallyMutatedInScope;
-
-  @override
-  DartType get type => substituteFor(baseElement.type);
-
-  @override
-  void visitChildren(ElementVisitor visitor) {
-    // TODO(brianwilkerson) We need to finish implementing the accessors used
-    // below so that we can safely invoke them.
-    super.visitChildren(visitor);
-    safelyVisitChild(baseElement.initializer, visitor);
-  }
-}
-
-/**
- * The type `void`.
- */
-abstract class VoidType implements DartType {
-  @override
-  VoidType substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes);
-}
-
-/**
- * A concrete implementation of a [VoidType].
- */
-class VoidTypeImpl extends TypeImpl implements VoidType {
-  /**
-   * The unique instance of this class.
-   */
-  static VoidTypeImpl _INSTANCE = new VoidTypeImpl();
-
-  /**
-   * Return the unique instance of this class.
-   */
-  static VoidTypeImpl get instance => _INSTANCE;
-
-  /**
-   * Prevent the creation of instances of this class.
-   */
-  VoidTypeImpl() : super(null, Keyword.VOID.syntax);
-
-  @override
-  int get hashCode => 2;
-
-  @override
-  bool get isVoid => true;
-
-  @override
-  bool operator ==(Object object) => identical(object, this);
-
-  @override
-  bool isMoreSpecificThan(DartType type,
-          [bool withDynamic = false, Set<Element> visitedElements]) =>
-      isSubtypeOf(type);
-
-  @override
-  bool isSubtypeOf(DartType type) {
-    // The only subtype relations that pertain to void are therefore:
-    // void <: void (by reflexivity)
-    // bottom <: void (as bottom is a subtype of all types).
-    // void <: dynamic (as dynamic is a supertype of all types)
-    return identical(type, this) || type.isDynamic;
-  }
-
-  @override
-  TypeImpl pruned(List<FunctionTypeAliasElement> prune) => this;
-
-  @override
-  VoidTypeImpl substitute2(
-      List<DartType> argumentTypes, List<DartType> parameterTypes,
-      [List<FunctionTypeAliasElement> prune]) => this;
-}
-
-/**
- * A visitor that visit all the elements recursively and fill the given [map].
- */
-class _BuildOffsetToElementMap extends GeneralizingElementVisitor {
-  final Map<int, Element> map;
-
-  _BuildOffsetToElementMap(this.map);
-
-  @override
-  void visitElement(Element element) {
-    int offset = element.nameOffset;
-    if (offset != -1) {
-      map[offset] = element;
-    }
-    super.visitElement(element);
-  }
-}