Revert "Move dart2js from sdk/lib/_internal/compiler to pkg/compiler"

pkg/compiler/lib/src/js_backend/runtime_types.dart

Index: pkg/compiler/lib/src/js_backend/runtime_types.dart
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types.dart b/pkg/compiler/lib/src/js_backend/runtime_types.dart
deleted file mode 100644
index cb4e509d5d91e9510b4699cb491457e946fd8441..0000000000000000000000000000000000000000
--- a/pkg/compiler/lib/src/js_backend/runtime_types.dart
+++ /dev/null
@@ -1,909 +0,0 @@
-// Copyright (c) 2013, 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.
-
-part of js_backend;
-
-/// For each class, stores the possible class subtype tests that could succeed.
-abstract class TypeChecks {
-  /// Get the set of checks required for class [element].
-  Iterable<TypeCheck> operator[](ClassElement element);
-  /// Get the iterator for all classes that need type checks.
-  Iterator<ClassElement> get iterator;
-}
-
-typedef jsAst.Expression OnVariableCallback(TypeVariableType variable);
-typedef bool ShouldEncodeTypedefCallback(TypedefType variable);
-
-class RuntimeTypes {
-  final Compiler compiler;
-  final TypeRepresentationGenerator representationGenerator;
-
-  final Map<ClassElement, Set<ClassElement>> rtiDependencies;
-  final Set<ClassElement> classesNeedingRti;
-  final Set<Element> methodsNeedingRti;
-  // The set of classes that use one of their type variables as expressions
-  // to get the runtime type.
-  final Set<ClassElement> classesUsingTypeVariableExpression;
-  // The set of type arguments tested against type variable bounds.
-  final Set<DartType> checkedTypeArguments;
-  // The set of tested type variable bounds.
-  final Set<DartType> checkedBounds;
-
-  JavaScriptBackend get backend => compiler.backend;
-
-  RuntimeTypes(Compiler compiler)
-      : this.compiler = compiler,
-        representationGenerator = new TypeRepresentationGenerator(compiler),
-        classesNeedingRti = new Set<ClassElement>(),
-        methodsNeedingRti = new Set<Element>(),
-        rtiDependencies = new Map<ClassElement, Set<ClassElement>>(),
-        classesUsingTypeVariableExpression = new Set<ClassElement>(),
-        checkedTypeArguments = new Set<DartType>(),
-        checkedBounds = new Set<DartType>();
-
-  Set<ClassElement> directlyInstantiatedArguments;
-  Set<ClassElement> allInstantiatedArguments;
-  Set<ClassElement> checkedArguments;
-
-  void registerRtiDependency(Element element, Element dependency) {
-    // We're not dealing with typedef for now.
-    if (!element.isClass || !dependency.isClass) return;
-    Set<ClassElement> classes =
-        rtiDependencies.putIfAbsent(element, () => new Set<ClassElement>());
-    classes.add(dependency);
-  }
-
-  void registerTypeVariableBoundsSubtypeCheck(DartType typeArgument,
-                                              DartType bound) {
-    checkedTypeArguments.add(typeArgument);
-    checkedBounds.add(bound);
-  }
-
-  bool usingFactoryWithTypeArguments = false;
-
-  /**
-   * Compute type arguments of classes that use one of their type variables in
-   * is-checks and add the is-checks that they imply.
-   *
-   * This function must be called after all is-checks have been registered.
-   *
-   * TODO(karlklose): move these computations into a function producing an
-   * immutable datastructure.
-   */
-  void addImplicitChecks(Universe universe,
-                         Iterable<ClassElement> classesUsingChecks) {
-    // If there are no classes that use their variables in checks, there is
-    // nothing to do.
-    if (classesUsingChecks.isEmpty) return;
-    Set<DartType> instantiatedTypes = universe.instantiatedTypes;
-    if (universe.usingFactoryWithTypeArguments) {
-      for (DartType type in instantiatedTypes) {
-        if (type.kind != TypeKind.INTERFACE) continue;
-        InterfaceType interface = type;
-        do {
-          for (DartType argument in interface.typeArguments) {
-            universe.registerIsCheck(argument, compiler);
-          }
-          interface = interface.element.supertype;
-        } while (interface != null && !instantiatedTypes.contains(interface));
-      }
-    } else {
-      // Find all instantiated types that are a subtype of a class that uses
-      // one of its type arguments in an is-check and add the arguments to the
-      // set of is-checks.
-      // TODO(karlklose): replace this with code that uses a subtype lookup
-      // datastructure in the world.
-      for (DartType type in instantiatedTypes) {
-        if (type.kind != TypeKind.INTERFACE) continue;
-        InterfaceType classType = type;
-        for (ClassElement cls in classesUsingChecks) {
-          InterfaceType current = classType;
-          do {
-            // We need the type as instance of its superclass anyway, so we just
-            // try to compute the substitution; if the result is [:null:], the
-            // classes are not related.
-            InterfaceType instance = current.asInstanceOf(cls);
-            if (instance == null) break;
-            for (DartType argument in instance.typeArguments) {
-              universe.registerIsCheck(argument, compiler);
-            }
-            current = current.element.supertype;
-          } while (current != null && !instantiatedTypes.contains(current));
-        }
-      }
-    }
-  }
-
-  void computeClassesNeedingRti() {
-    // Find the classes that need runtime type information. Such
-    // classes are:
-    // (1) used in a is check with type variables,
-    // (2) dependencies of classes in (1),
-    // (3) subclasses of (2) and (3).
-    void potentiallyAddForRti(ClassElement cls) {
-      assert(invariant(cls, cls.isDeclaration));
-      if (cls.typeVariables.isEmpty) return;
-      if (classesNeedingRti.contains(cls)) return;
-      classesNeedingRti.add(cls);
-
-      // TODO(ngeoffray): This should use subclasses, not subtypes.
-      Iterable<ClassElement> classes = compiler.world.subtypesOf(cls);
-      classes.forEach((ClassElement sub) {
-        potentiallyAddForRti(sub);
-      });
-
-      Set<ClassElement> dependencies = rtiDependencies[cls];
-      if (dependencies != null) {
-        dependencies.forEach((ClassElement other) {
-          potentiallyAddForRti(other);
-        });
-      }
-    }
-
-    Set<ClassElement> classesUsingTypeVariableTests = new Set<ClassElement>();
-    compiler.resolverWorld.isChecks.forEach((DartType type) {
-      if (type.isTypeVariable) {
-        TypeVariableElement variable = type.element;
-        classesUsingTypeVariableTests.add(variable.typeDeclaration);
-      }
-    });
-    // Add is-checks that result from classes using type variables in checks.
-    addImplicitChecks(compiler.resolverWorld, classesUsingTypeVariableTests);
-    // Add the rti dependencies that are implicit in the way the backend
-    // generates code: when we create a new [List], we actually create
-    // a JSArray in the backend and we need to add type arguments to
-    // the calls of the list constructor whenever we determine that
-    // JSArray needs type arguments.
-    // TODO(karlklose): make this dependency visible from code.
-    if (backend.jsArrayClass != null) {
-      registerRtiDependency(backend.jsArrayClass, compiler.listClass);
-    }
-    // Compute the set of all classes and methods that need runtime type
-    // information.
-    compiler.resolverWorld.isChecks.forEach((DartType type) {
-      if (type.isInterfaceType) {
-        InterfaceType itf = type;
-        if (!itf.treatAsRaw) {
-          potentiallyAddForRti(itf.element);
-        }
-      } else {
-        ClassElement contextClass = Types.getClassContext(type);
-        if (contextClass != null) {
-          // [type] contains type variables (declared in [contextClass]) if
-          // [contextClass] is non-null. This handles checks against type
-          // variables and function types containing type variables.
-          potentiallyAddForRti(contextClass);
-        }
-        if (type.isFunctionType) {
-          void analyzeMethod(TypedElement method) {
-            DartType memberType = method.type;
-            ClassElement contextClass = Types.getClassContext(memberType);
-            if (contextClass != null &&
-                compiler.types.isPotentialSubtype(memberType, type)) {
-              potentiallyAddForRti(contextClass);
-              methodsNeedingRti.add(method);
-            }
-          }
-          compiler.resolverWorld.closuresWithFreeTypeVariables.forEach(
-              analyzeMethod);
-          compiler.resolverWorld.callMethodsWithFreeTypeVariables.forEach(
-              analyzeMethod);
-        }
-      }
-    });
-    if (compiler.enableTypeAssertions) {
-      void analyzeMethod(TypedElement method) {
-        DartType memberType = method.type;
-        ClassElement contextClass = Types.getClassContext(memberType);
-        if (contextClass != null) {
-          potentiallyAddForRti(contextClass);
-          methodsNeedingRti.add(method);
-        }
-      }
-      compiler.resolverWorld.closuresWithFreeTypeVariables.forEach(
-          analyzeMethod);
-      compiler.resolverWorld.callMethodsWithFreeTypeVariables.forEach(
-          analyzeMethod);
-    }
-    // Add the classes that need RTI because they use a type variable as
-    // expression.
-    classesUsingTypeVariableExpression.forEach(potentiallyAddForRti);
-  }
-
-  TypeChecks cachedRequiredChecks;
-
-  TypeChecks get requiredChecks {
-    if (cachedRequiredChecks == null) {
-      computeRequiredChecks();
-    }
-    assert(cachedRequiredChecks != null);
-    return cachedRequiredChecks;
-  }
-
-  /// Compute the required type checkes and substitutions for the given
-  /// instantitated and checked classes.
-  TypeChecks computeChecks(Set<ClassElement> instantiated,
-                           Set<ClassElement> checked) {
-    // Run through the combination of instantiated and checked
-    // arguments and record all combination where the element of a checked
-    // argument is a superclass of the element of an instantiated type.
-    TypeCheckMapping result = new TypeCheckMapping();
-    for (ClassElement element in instantiated) {
-      if (checked.contains(element)) {
-        result.add(element, element, null);
-      }
-      // Find all supertypes of [element] in [checkedArguments] and add checks
-      // and precompute the substitutions for them.
-      assert(invariant(element, element.allSupertypes != null,
-             message: 'Supertypes have not been computed for $element.'));
-      for (DartType supertype in element.allSupertypes) {
-        ClassElement superelement = supertype.element;
-        if (checked.contains(superelement)) {
-          Substitution substitution =
-              computeSubstitution(element, superelement);
-          result.add(element, superelement, substitution);
-        }
-      }
-    }
-    return result;
-  }
-
-  void computeRequiredChecks() {
-    Set<DartType> isChecks = compiler.codegenWorld.isChecks;
-    bool hasFunctionTypeCheck =
-        isChecks.any((type) => identical(type.kind, TypeKind.FUNCTION));
-    Set<DartType> instantiatedTypesAndClosures = hasFunctionTypeCheck
-        ? computeInstantiatedTypesAndClosures(compiler.codegenWorld)
-        : compiler.codegenWorld.instantiatedTypes;
-    computeInstantiatedArguments(instantiatedTypesAndClosures, isChecks);
-    computeCheckedArguments(instantiatedTypesAndClosures, isChecks);
-    cachedRequiredChecks =
-        computeChecks(allInstantiatedArguments, checkedArguments);
-  }
-
-  Set<DartType> computeInstantiatedTypesAndClosures(Universe universe) {
-    Set<DartType> instantiatedTypes =
-        new Set<DartType>.from(universe.instantiatedTypes);
-    for (DartType instantiatedType in universe.instantiatedTypes) {
-      if (instantiatedType.isInterfaceType) {
-        InterfaceType interface = instantiatedType;
-        FunctionType callType = interface.callType;
-        if (callType != null) {
-          instantiatedTypes.add(callType);
-        }
-      }
-    }
-    for (FunctionElement element in universe.staticFunctionsNeedingGetter) {
-      instantiatedTypes.add(element.type);
-    }
-    // TODO(johnniwinther): We should get this information through the
-    // [neededClasses] computed in the emitter instead of storing it and pulling
-    // it from resolution, but currently it would introduce a cyclic dependency
-    // between [computeRequiredChecks] and [computeNeededClasses].
-    for (TypedElement element in compiler.resolverWorld.closurizedMembers) {
-      instantiatedTypes.add(element.type);
-    }
-    return instantiatedTypes;
-  }
-
-  /**
-   * Collects all types used in type arguments of instantiated types.
-   *
-   * This includes type arguments used in supertype relations, because we may
-   * have a type check against this supertype that includes a check against
-   * the type arguments.
-   */
-  void computeInstantiatedArguments(Set<DartType> instantiatedTypes,
-                                    Set<DartType> isChecks) {
-    ArgumentCollector superCollector = new ArgumentCollector(backend);
-    ArgumentCollector directCollector = new ArgumentCollector(backend);
-    FunctionArgumentCollector functionArgumentCollector =
-        new FunctionArgumentCollector(backend);
-
-    // We need to add classes occuring in function type arguments, like for
-    // instance 'I' for [: o is C<f> :] where f is [: typedef I f(); :].
-    void collectFunctionTypeArguments(Iterable<DartType> types) {
-      for (DartType type in types) {
-        functionArgumentCollector.collect(type);
-      }
-    }
-    collectFunctionTypeArguments(isChecks);
-    collectFunctionTypeArguments(checkedBounds);
-
-    void collectTypeArguments(Iterable<DartType> types,
-                              {bool isTypeArgument: false}) {
-      for (DartType type in types) {
-        directCollector.collect(type, isTypeArgument: isTypeArgument);
-        if (type.isInterfaceType) {
-          ClassElement cls = type.element;
-          for (DartType supertype in cls.allSupertypes) {
-            superCollector.collect(supertype, isTypeArgument: isTypeArgument);
-          }
-        }
-      }
-    }
-    collectTypeArguments(instantiatedTypes);
-    collectTypeArguments(checkedTypeArguments, isTypeArgument: true);
-
-    for (ClassElement cls in superCollector.classes.toList()) {
-      for (DartType supertype in cls.allSupertypes) {
-        superCollector.collect(supertype);
-      }
-    }
-
-    directlyInstantiatedArguments =
-        directCollector.classes..addAll(functionArgumentCollector.classes);
-    allInstantiatedArguments =
-        superCollector.classes..addAll(directlyInstantiatedArguments);
-  }
-
-  /// Collects all type arguments used in is-checks.
-  void computeCheckedArguments(Set<DartType> instantiatedTypes,
-                               Set<DartType> isChecks) {
-    ArgumentCollector collector = new ArgumentCollector(backend);
-    FunctionArgumentCollector functionArgumentCollector =
-        new FunctionArgumentCollector(backend);
-
-    // We need to add types occuring in function type arguments, like for
-    // instance 'J' for [: (J j) {} is f :] where f is
-    // [: typedef void f(I i); :] and 'J' is a subtype of 'I'.
-    void collectFunctionTypeArguments(Iterable<DartType> types) {
-      for (DartType type in types) {
-        functionArgumentCollector.collect(type);
-      }
-    }
-    collectFunctionTypeArguments(instantiatedTypes);
-    collectFunctionTypeArguments(checkedTypeArguments);
-
-    void collectTypeArguments(Iterable<DartType> types,
-                              {bool isTypeArgument: false}) {
-      for (DartType type in types) {
-        collector.collect(type, isTypeArgument: isTypeArgument);
-      }
-    }
-    collectTypeArguments(isChecks);
-    collectTypeArguments(checkedBounds, isTypeArgument: true);
-
-    checkedArguments =
-        collector.classes..addAll(functionArgumentCollector.classes);
-  }
-
-  Set<ClassElement> getClassesUsedInSubstitutions(JavaScriptBackend backend,
-                                                  TypeChecks checks) {
-    Set<ClassElement> instantiated = new Set<ClassElement>();
-    ArgumentCollector collector = new ArgumentCollector(backend);
-    for (ClassElement target in checks) {
-      instantiated.add(target);
-      for (TypeCheck check in checks[target]) {
-        Substitution substitution = check.substitution;
-        if (substitution != null) {
-          collector.collectAll(substitution.arguments);
-        }
-      }
-    }
-    return instantiated..addAll(collector.classes);
-  }
-
-  Set<ClassElement> getRequiredArgumentClasses(JavaScriptBackend backend) {
-    Set<ClassElement> requiredArgumentClasses =
-        new Set<ClassElement>.from(
-            getClassesUsedInSubstitutions(backend, requiredChecks));
-    return requiredArgumentClasses
-        ..addAll(directlyInstantiatedArguments)
-        ..addAll(checkedArguments);
-  }
-
-  String getTypeRepresentationForTypeConstant(DartType type) {
-    JavaScriptBackend backend = compiler.backend;
-    Namer namer = backend.namer;
-    if (type.isDynamic) return namer.getRuntimeTypeName(null);
-    String name = namer.uniqueNameForTypeConstantElement(type.element);
-    if (!type.element.isClass) return name;
-    InterfaceType interface = type;
-    List<DartType> variables = interface.element.typeVariables;
-    // Type constants can currently only be raw types, so there is no point
-    // adding ground-term type parameters, as they would just be 'dynamic'.
-    // TODO(sra): Since the result string is used only in constructing constant
-    // names, it would result in more readable names if the final string was a
-    // legal JavaScript identifer.
-    if (variables.isEmpty) return name;
-    String arguments =
-        new List.filled(variables.length, 'dynamic').join(', ');
-    return '$name<$arguments>';
-  }
-
-  // TODO(karlklose): maybe precompute this value and store it in typeChecks?
-  bool isTrivialSubstitution(ClassElement cls, ClassElement check) {
-    if (cls.isClosure) {
-      // TODO(karlklose): handle closures.
-      return true;
-    }
-
-    // If there are no type variables or the type is the same, we do not need
-    // a substitution.
-    if (check.typeVariables.isEmpty || cls == check) {
-      return true;
-    }
-
-    InterfaceType originalType = cls.thisType;
-    InterfaceType type = originalType.asInstanceOf(check);
-    // [type] is not a subtype of [check]. we do not generate a check and do not
-    // need a substitution.
-    if (type == null) return true;
-
-    // Run through both lists of type variables and check if the type variables
-    // are identical at each position. If they are not, we need to calculate a
-    // substitution function.
-    List<DartType> variables = cls.typeVariables;
-    List<DartType> arguments = type.typeArguments;
-    if (variables.length != arguments.length) {
-      return false;
-    }
-    for (int index = 0; index < variables.length; index++) {
-      if (variables[index].element != arguments[index].element) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  /**
-   * Compute a JavaScript expression that describes the necessary substitution
-   * for type arguments in a subtype test.
-   *
-   * The result can be:
-   *  1) [:null:], if no substituted check is necessary, because the
-   *     type variables are the same or there are no type variables in the class
-   *     that is checked for.
-   *  2) A list expression describing the type arguments to be used in the
-   *     subtype check, if the type arguments to be used in the check do not
-   *     depend on the type arguments of the object.
-   *  3) A function mapping the type variables of the object to be checked to
-   *     a list expression.
-   */
-  jsAst.Expression getSupertypeSubstitution(
-       ClassElement cls,
-       ClassElement check,
-       {bool alwaysGenerateFunction: false}) {
-    Substitution substitution = getSubstitution(cls, check);
-    if (substitution != null) {
-      return substitution.getCode(this, alwaysGenerateFunction);
-    } else {
-      return null;
-    }
-  }
-
-  Substitution getSubstitution(ClassElement cls, ClassElement other) {
-    // Look for a precomputed check.
-    for (TypeCheck check in cachedRequiredChecks[cls]) {
-      if (check.cls == other) {
-        return check.substitution;
-      }
-    }
-    // There is no precomputed check for this pair (because the check is not
-    // done on type arguments only.  Compute a new substitution.
-    return computeSubstitution(cls, other);
-  }
-
-  Substitution computeSubstitution(ClassElement cls, ClassElement check,
-                                   { bool alwaysGenerateFunction: false }) {
-    if (isTrivialSubstitution(cls, check)) return null;
-
-    // Unnamed mixin application classes do not need substitutions, because they
-    // are never instantiated and their checks are overwritten by the class that
-    // they are mixed into.
-    InterfaceType type = cls.thisType;
-    InterfaceType target = type.asInstanceOf(check);
-    List<DartType> typeVariables = cls.typeVariables;
-    if (typeVariables.isEmpty && !alwaysGenerateFunction) {
-      return new Substitution.list(target.typeArguments);
-    } else {
-      return new Substitution.function(target.typeArguments, typeVariables);
-    }
-  }
-
-  jsAst.Expression getSubstitutionRepresentation(
-      List<DartType> types,
-      OnVariableCallback onVariable) {
-    List<jsAst.ArrayElement> elements = <jsAst.ArrayElement>[];
-    int index = 0;
-    for (DartType type in types) {
-      jsAst.Expression representation = getTypeRepresentation(type, onVariable);
-      elements.add(new jsAst.ArrayElement(index++, representation));
-    }
-    return new jsAst.ArrayInitializer(index, elements);
-  }
-
-  jsAst.Expression getTypeEncoding(DartType type,
-                                   {bool alwaysGenerateFunction: false}) {
-    ClassElement contextClass = Types.getClassContext(type);
-    jsAst.Expression onVariable(TypeVariableType v) {
-      return new jsAst.VariableUse(v.name);
-    };
-    jsAst.Expression encoding = getTypeRepresentation(type, onVariable);
-    if (contextClass == null && !alwaysGenerateFunction) {
-      return encoding;
-    } else {
-      List<String> parameters = const <String>[];
-      if (contextClass != null) {
-        parameters = contextClass.typeVariables.map((type) {
-            return type.toString();
-        }).toList();
-      }
-      return js('function(#) { return # }', [parameters, encoding]);
-    }
-  }
-
-  jsAst.Expression getSignatureEncoding(DartType type, jsAst.Expression this_) {
-    ClassElement contextClass = Types.getClassContext(type);
-    jsAst.Expression encoding =
-        getTypeEncoding(type, alwaysGenerateFunction: true);
-    if (contextClass != null) {
-      JavaScriptBackend backend = compiler.backend;
-      String contextName = backend.namer.getNameOfClass(contextClass);
-      return js('function () { return #(#, #, #); }',
-          [ backend.namer.elementAccess(backend.getComputeSignature()),
-              encoding, this_, js.string(contextName) ]);
-    } else {
-      return encoding;
-    }
-  }
-
-  String getTypeRepresentationWithHashes(DartType type,
-                                         OnVariableCallback onVariable) {
-    // Create a type representation.  For type variables call the original
-    // callback for side effects and return a template placeholder.
-    jsAst.Expression representation = getTypeRepresentation(type, (variable) {
-      onVariable(variable);
-      return new jsAst.LiteralString('#');
-    });
-    return jsAst.prettyPrint(representation, compiler).buffer.toString();
-  }
-
-  jsAst.Expression getTypeRepresentation(
-      DartType type,
-      OnVariableCallback onVariable,
-      [ShouldEncodeTypedefCallback shouldEncodeTypedef]) {
-    return representationGenerator.getTypeRepresentation(
-        type, onVariable, shouldEncodeTypedef);
-  }
-
-  bool isSimpleFunctionType(FunctionType type) {
-    if (!type.returnType.isDynamic) return false;
-    if (!type.optionalParameterTypes.isEmpty) return false;
-    if (!type.namedParameterTypes.isEmpty) return false;
-    for (DartType parameter in type.parameterTypes ) {
-      if (!parameter.isDynamic) return false;
-    }
-    return true;
-  }
-
-  static bool hasTypeArguments(DartType type) {
-    if (type is InterfaceType) {
-      InterfaceType interfaceType = type;
-      return !interfaceType.treatAsRaw;
-    }
-    return false;
-  }
-
-  static int getTypeVariableIndex(TypeVariableElement variable) {
-    ClassElement classElement = variable.enclosingClass;
-    List<DartType> variables = classElement.typeVariables;
-    for (int index = 0; index < variables.length; index++) {
-      if (variables[index].element == variable) return index;
-    }
-    throw invariant(variable, false,
-                    message: "Couldn't find type-variable index");
-  }
-
-  /// Return all classes that are referenced in the type of the function, i.e.,
-  /// in the return type or the argument types.
-  Set<ClassElement> getReferencedClasses(FunctionType type) {
-    FunctionArgumentCollector collector =
-        new FunctionArgumentCollector(backend);
-    collector.collect(type);
-    return collector.classes;
-  }
-}
-
-class TypeRepresentationGenerator extends DartTypeVisitor {
-  final Compiler compiler;
-  OnVariableCallback onVariable;
-  ShouldEncodeTypedefCallback shouldEncodeTypedef;
-
-  JavaScriptBackend get backend => compiler.backend;
-  Namer get namer => backend.namer;
-
-  TypeRepresentationGenerator(Compiler this.compiler);
-
-  /**
-   * Creates a type representation for [type]. [onVariable] is called to provide
-   * the type representation for type variables.
-   */
-  jsAst.Expression getTypeRepresentation(
-      DartType type,
-      OnVariableCallback onVariable,
-      ShouldEncodeTypedefCallback encodeTypedef) {
-    this.onVariable = onVariable;
-    this.shouldEncodeTypedef =
-        (encodeTypedef != null) ? encodeTypedef : (TypedefType type) => false;
-    jsAst.Expression representation = visit(type);
-    this.onVariable = null;
-    this.shouldEncodeTypedef = null;
-    return representation;
-  }
-
-  jsAst.Expression getJavaScriptClassName(Element element) {
-    return namer.elementAccess(element);
-  }
-
-  visit(DartType type) {
-    return type.accept(this, null);
-  }
-
-  visitTypeVariableType(TypeVariableType type, _) {
-    return onVariable(type);
-  }
-
-  visitDynamicType(DynamicType type, _) {
-    return js('null');
-  }
-
-  visitInterfaceType(InterfaceType type, _) {
-    jsAst.Expression name = getJavaScriptClassName(type.element);
-    return type.treatAsRaw ? name : visitList(type.typeArguments, head: name);
-  }
-
-  jsAst.Expression visitList(List<DartType> types, {jsAst.Expression head}) {
-    int index = 0;
-    List<jsAst.ArrayElement> elements = <jsAst.ArrayElement>[];
-    if (head != null) {
-      elements.add(new jsAst.ArrayElement(0, head));
-      index++;
-    }
-    for (DartType type in types) {
-      elements.add(new jsAst.ArrayElement(index++, visit(type)));
-    }
-    return new jsAst.ArrayInitializer(elements.length, elements);
-  }
-
-  visitFunctionType(FunctionType type, _) {
-    List<jsAst.Property> properties = <jsAst.Property>[];
-
-    void addProperty(String name, jsAst.Expression value) {
-      properties.add(new jsAst.Property(js.string(name), value));
-    }
-
-    jsAst.LiteralString name = js.string(namer.getFunctionTypeName(type));
-    addProperty(namer.functionTypeTag(), name);
-    if (type.returnType.isVoid) {
-      addProperty(namer.functionTypeVoidReturnTag(), js('true'));
-    } else if (!type.returnType.treatAsDynamic) {
-      addProperty(namer.functionTypeReturnTypeTag(), visit(type.returnType));
-    }
-    if (!type.parameterTypes.isEmpty) {
-      addProperty(namer.functionTypeRequiredParametersTag(),
-                  visitList(type.parameterTypes));
-    }
-    if (!type.optionalParameterTypes.isEmpty) {
-      addProperty(namer.functionTypeOptionalParametersTag(),
-                  visitList(type.optionalParameterTypes));
-    }
-    if (!type.namedParameterTypes.isEmpty) {
-      List<jsAst.Property> namedArguments = <jsAst.Property>[];
-      List<String> names = type.namedParameters;
-      List<DartType> types = type.namedParameterTypes;
-      assert(types.length == names.length);
-      for (int index = 0; index < types.length; index++) {
-        jsAst.Expression name = js.string(names[index]);
-        namedArguments.add(new jsAst.Property(name, visit(types[index])));
-      }
-      addProperty(namer.functionTypeNamedParametersTag(),
-                  new jsAst.ObjectInitializer(namedArguments));
-    }
-    return new jsAst.ObjectInitializer(properties);
-  }
-
-  visitMalformedType(MalformedType type, _) {
-    // Treat malformed types as dynamic at runtime.
-    return js('null');
-  }
-
-  visitVoidType(VoidType type, _) {
-    // TODO(ahe): Reify void type ("null" means "dynamic").
-    return js('null');
-  }
-
-  visitTypedefType(TypedefType type, _) {
-    bool shouldEncode = shouldEncodeTypedef(type);
-    DartType unaliasedType = type.unalias(compiler);
-    if (shouldEncode) {
-      jsAst.ObjectInitializer initializer = unaliasedType.accept(this, null);
-      // We have to encode the aliased type.
-      jsAst.Expression name = getJavaScriptClassName(type.element);
-      jsAst.Expression encodedTypedef =
-          type.treatAsRaw ? name : visitList(type.typeArguments, head: name);
-
-      // Add it to the function-type object.
-      jsAst.LiteralString tag = js.string(namer.typedefTag());
-      initializer.properties.add(new jsAst.Property(tag, encodedTypedef));
-      return initializer;
-    } else {
-      return unaliasedType.accept(this, null);
-    }
-  }
-
-  visitType(DartType type, _) {
-    compiler.internalError(NO_LOCATION_SPANNABLE,
-        'Unexpected type: $type (${type.kind}).');
-  }
-}
-
-
-class TypeCheckMapping implements TypeChecks {
-  final Map<ClassElement, Set<TypeCheck>> map =
-      new Map<ClassElement, Set<TypeCheck>>();
-
-  Iterable<TypeCheck> operator[](ClassElement element) {
-    Set<TypeCheck> result = map[element];
-    return result != null ? result : const <TypeCheck>[];
-  }
-
-  void add(ClassElement cls, ClassElement check, Substitution substitution) {
-    map.putIfAbsent(cls, () => new Set<TypeCheck>());
-    map[cls].add(new TypeCheck(check, substitution));
-  }
-
-  Iterator<ClassElement> get iterator => map.keys.iterator;
-
-  String toString() {
-    StringBuffer sb = new StringBuffer();
-    for (ClassElement holder in this) {
-      for (ClassElement check in [holder]) {
-        sb.write('${holder.name}.' '${check.name}, ');
-      }
-    }
-    return '[$sb]';
-  }
-}
-
-class ArgumentCollector extends DartTypeVisitor {
-  final JavaScriptBackend backend;
-  final Set<ClassElement> classes = new Set<ClassElement>();
-
-  ArgumentCollector(this.backend);
-
-  collect(DartType type, {bool isTypeArgument: false}) {
-    type.accept(this, isTypeArgument);
-  }
-
-  /// Collect all types in the list as if they were arguments of an
-  /// InterfaceType.
-  collectAll(List<DartType> types) {
-    for (DartType type in types) {
-      type.accept(this, true);
-    }
-  }
-
-  visitType(DartType type, _) {
-    // Do nothing.
-  }
-
-  visitDynamicType(DynamicType type, _) {
-    // Do not collect [:dynamic:].
-  }
-
-  visitTypedefType(TypedefType type, bool isTypeArgument) {
-    type.unalias(backend.compiler).accept(this, isTypeArgument);
-  }
-
-  visitInterfaceType(InterfaceType type, bool isTypeArgument) {
-    if (isTypeArgument) classes.add(type.element);
-    type.visitChildren(this, true);
-  }
-
-  visitFunctionType(FunctionType type, _) {
-    type.visitChildren(this, true);
-  }
-}
-
-class FunctionArgumentCollector extends DartTypeVisitor {
-  final JavaScriptBackend backend;
-  final Set<ClassElement> classes = new Set<ClassElement>();
-
-  FunctionArgumentCollector(this.backend);
-
-  collect(DartType type) {
-    type.accept(this, false);
-  }
-
-  /// Collect all types in the list as if they were arguments of an
-  /// InterfaceType.
-  collectAll(Link<DartType> types) {
-    for (Link<DartType> link = types; !link.isEmpty; link = link.tail) {
-      link.head.accept(this, true);
-    }
-  }
-
-  visitType(DartType type, _) {
-    // Do nothing.
-  }
-
-  visitDynamicType(DynamicType type, _) {
-    // Do not collect [:dynamic:].
-  }
-
-  visitTypedefType(TypedefType type, bool inFunctionType) {
-    type.unalias(backend.compiler).accept(this, inFunctionType);
-  }
-
-  visitInterfaceType(InterfaceType type, bool inFunctionType) {
-    if (inFunctionType) {
-      classes.add(type.element);
-    }
-    type.visitChildren(this, inFunctionType);
-  }
-
-  visitFunctionType(FunctionType type, _) {
-    type.visitChildren(this, true);
-  }
-}
-
-/**
- * Representation of the substitution of type arguments
- * when going from the type of a class to one of its supertypes.
- *
- * For [:class B<T> extends A<List<T>, int>:], the substitution is
- * the representation of [: (T) => [<List, T>, int] :].  For more details
- * of the representation consult the documentation of
- * [getSupertypeSubstitution].
- */
-class Substitution {
-  final bool isFunction;
-  final List<DartType> arguments;
-  final List<DartType> parameters;
-
-  Substitution.list(this.arguments)
-      : isFunction = false,
-        parameters = const <DartType>[];
-
-  Substitution.function(this.arguments, this.parameters)
-      : isFunction = true;
-
-  jsAst.Expression getCode(RuntimeTypes rti, bool ensureIsFunction) {
-    jsAst.Expression declaration(TypeVariableType variable) {
-      return new jsAst.Parameter(
-          rti.backend.namer.safeVariableName(variable.name));
-    }
-
-    jsAst.Expression use(TypeVariableType variable) {
-      return new jsAst.VariableUse(
-          rti.backend.namer.safeVariableName(variable.name));
-    }
-
-    jsAst.Expression value =
-        rti.getSubstitutionRepresentation(arguments, use);
-    if (isFunction) {
-      Iterable<jsAst.Expression> formals = parameters.map(declaration);
-      return js('function(#) { return # }', [formals, value]);
-    } else if (ensureIsFunction) {
-      return js('function() { return # }', value);
-    } else {
-      return value;
-    }
-  }
-}
-
-/**
- * A pair of a class that we need a check against and the type argument
- * substition for this check.
- */
-class TypeCheck {
-  final ClassElement cls;
-  final Substitution substitution;
-  final int hashCode = (nextHash++) & 0x3fffffff;
-  static int nextHash = 49;
-
-  TypeCheck(this.cls, this.substitution);
-}