Merge CommonElements and BackendHelpers!

pkg/compiler/lib/src/common_elements.dart

Index: pkg/compiler/lib/src/common_elements.dart
diff --git a/pkg/compiler/lib/src/common_elements.dart b/pkg/compiler/lib/src/common_elements.dart
index 29a1a004e159508e5e0720b5a5f35944eb140f1e..fd748c64bea8b7531790174493f17cd9bde98557 100644
--- a/pkg/compiler/lib/src/common_elements.dart
+++ b/pkg/compiler/lib/src/common_elements.dart
@@ -5,206 +5,338 @@
 // TODO(sigmund): rename and move to common/elements.dart
 library dart2js.type_system;
 
-import 'common/names.dart' show Uris;
+import 'common/names.dart' show Identifiers, Uris;
+import 'js_backend/constant_system_javascript.dart';
 import 'elements/types.dart';
+import 'elements/elements.dart' show PublicName;
 import 'elements/entities.dart';
+import 'js_backend/backend.dart' show JavaScriptBackend;
+import 'universe/call_structure.dart' show CallStructure;
+import 'universe/selector.dart' show Selector;
 import 'universe/call_structure.dart';
 
 /// The common elements and types in Dart.
-abstract class CommonElements {
+class CommonElements {
+  final ElementEnvironment _env;
+
+  CommonElements(this._env);
+
   /// The `Object` class defined in 'dart:core'.
-  ClassEntity get objectClass;
+  ClassEntity _objectClass;
+  ClassEntity get objectClass =>
+      _objectClass ??= _findClass(coreLibrary, 'Object');
 
   /// The `bool` class defined in 'dart:core'.
-  ClassEntity get boolClass;
+  ClassEntity _boolClass;
+  ClassEntity get boolClass => _boolClass ??= _findClass(coreLibrary, 'bool');
 
   /// The `num` class defined in 'dart:core'.
-  ClassEntity get numClass;
+  ClassEntity _numClass;
+  ClassEntity get numClass => _numClass ??= _findClass(coreLibrary, 'num');
 
   /// The `int` class defined in 'dart:core'.
-  ClassEntity get intClass;
+  ClassEntity _intClass;
+  ClassEntity get intClass => _intClass ??= _findClass(coreLibrary, 'int');
 
   /// The `double` class defined in 'dart:core'.
-  ClassEntity get doubleClass;
-
-  /// The `Resource` class defined in 'dart:core'.
-  ClassEntity get resourceClass;
+  ClassEntity _doubleClass;
+  ClassEntity get doubleClass =>
+      _doubleClass ??= _findClass(coreLibrary, 'double');
 
   /// The `String` class defined in 'dart:core'.
-  ClassEntity get stringClass;
-
-  /// The `Symbol` class defined in 'dart:core'.
-  ClassEntity get symbolClass;
+  ClassEntity _stringClass;
+  ClassEntity get stringClass =>
+      _stringClass ??= _findClass(coreLibrary, 'String');
 
   /// The `Function` class defined in 'dart:core'.
-  ClassEntity get functionClass;
+  ClassEntity _functionClass;
+  ClassEntity get functionClass =>
+      _functionClass ??= _findClass(coreLibrary, 'Function');
+
+  /// The `Resource` class defined in 'dart:core'.
+  ClassEntity _resourceClass;
+  ClassEntity get resourceClass =>
+      _resourceClass ??= _findClass(coreLibrary, 'Resource');
+
+  /// The `Symbol` class defined in 'dart:core'.
+  ClassEntity _symbolClass;
+  ClassEntity get symbolClass =>
+      _symbolClass ??= _findClass(coreLibrary, 'Symbol');
 
   /// The `Null` class defined in 'dart:core'.
-  ClassEntity get nullClass;
+  ClassEntity _nullClass;
+  ClassEntity get nullClass => _nullClass ??= _findClass(coreLibrary, 'Null');
 
   /// The `Type` class defined in 'dart:core'.
-  ClassEntity get typeClass;
+  ClassEntity _typeClass;
+  ClassEntity get typeClass => _typeClass ??= _findClass(coreLibrary, 'Type');
 
   /// The `StackTrace` class defined in 'dart:core';
-  ClassEntity get stackTraceClass;
+  ClassEntity _stackTraceClass;
+  ClassEntity get stackTraceClass =>
+      _stackTraceClass ??= _findClass(coreLibrary, 'StackTrace');
 
   /// The `List` class defined in 'dart:core';
-  ClassEntity get listClass;
+  ClassEntity _listClass;
+  ClassEntity get listClass => _listClass ??= _findClass(coreLibrary, 'List');
 
   /// The `Map` class defined in 'dart:core';
-  ClassEntity get mapClass;
+  ClassEntity _mapClass;
+  ClassEntity get mapClass => _mapClass ??= _findClass(coreLibrary, 'Map');
 
   /// The `Iterable` class defined in 'dart:core';
-  ClassEntity get iterableClass;
+  ClassEntity _iterableClass;
+  ClassEntity get iterableClass =>
+      _iterableClass ??= _findClass(coreLibrary, 'Iterable');
 
   /// The `Future` class defined in 'async';.
-  ClassEntity get futureClass;
+  ClassEntity _futureClass;
+  ClassEntity get futureClass =>
+      _futureClass ??= _findClass(asyncLibrary, 'Future');
 
   /// The `Stream` class defined in 'async';
-  ClassEntity get streamClass;
+  ClassEntity _streamClass;
+  ClassEntity get streamClass =>
+      _streamClass ??= _findClass(asyncLibrary, 'Stream');
 
   /// The dart:core library.
-  LibraryEntity get coreLibrary;
+  LibraryEntity _coreLibrary;
+  LibraryEntity get coreLibrary =>
+      _coreLibrary ??= _env.lookupLibrary(Uris.dart_core, required: true);
 
   /// The dart:async library.
-  LibraryEntity get asyncLibrary;
+  LibraryEntity _asyncLibrary;
+  LibraryEntity get asyncLibrary =>
+      _asyncLibrary ??= _env.lookupLibrary(Uris.dart_async);
 
   /// The dart:mirrors library. Null if the program doesn't access dart:mirrors.
-  LibraryEntity get mirrorsLibrary;
+  LibraryEntity _mirrorsLibrary;
+  LibraryEntity get mirrorsLibrary =>
+      _mirrorsLibrary ??= _env.lookupLibrary(Uris.dart_mirrors);
 
   /// The dart:typed_data library.
-  LibraryEntity get typedDataLibrary;
+  LibraryEntity _typedDataLibrary;
+  LibraryEntity get typedDataLibrary =>
+      _typedDataLibrary ??= _env.lookupLibrary(Uris.dart__native_typed_data);
+
+  LibraryEntity _jsHelperLibrary;
+  LibraryEntity get jsHelperLibrary =>
+      _jsHelperLibrary ??= _env.lookupLibrary(Uris.dart__js_helper);
+
+  LibraryEntity _interceptorsLibrary;
+  LibraryEntity get interceptorsLibrary =>
+      _interceptorsLibrary ??= _env.lookupLibrary(Uris.dart__interceptors);
+
+  LibraryEntity _foreignLibrary;
+  LibraryEntity get foreignLibrary =>
+      _foreignLibrary ??= _env.lookupLibrary(Uris.dart__foreign_helper);
+
+  LibraryEntity _isolateHelperLibrary;
+  LibraryEntity get isolateHelperLibrary =>
+      _isolateHelperLibrary ??= _env.lookupLibrary(Uris.dart__isolate_helper);
+
+  /// Reference to the internal library to lookup functions to always inline.
+  LibraryEntity _internalLibrary;
+  LibraryEntity get internalLibrary =>
+      _internalLibrary ??= _env.lookupLibrary(Uris.dart__internal);
 
   /// The `NativeTypedData` class from dart:typed_data.
-  ClassEntity get typedDataClass;
+  ClassEntity _typedDataClass;
+  ClassEntity get typedDataClass =>
+      _typedDataClass ??= _findClass(typedDataLibrary, 'NativeTypedData');
 
   /// Constructor of the `Symbol` class. This getter will ensure that `Symbol`
   /// is resolved and lookup the constructor on demand.
-  ConstructorEntity get symbolConstructor;
+  ConstructorEntity _symbolConstructor;
+  ConstructorEntity get symbolConstructor =>
+      _symbolConstructor ??= _findConstructor(symbolClass, '');
 
   /// Whether [element] is the same as [symbolConstructor]. Used to check
   /// for the constructor without computing it until it is likely to be seen.
   // TODO(johnniwinther): Change type of [e] to [MemberEntity].
-  bool isSymbolConstructor(Entity e);
+  bool isSymbolConstructor(Entity e) => e == symbolConstructor;
 
   /// The `MirrorSystem` class in dart:mirrors.
-  ClassEntity get mirrorSystemClass;
+  ClassEntity _mirrorSystemClass;
+  ClassEntity get mirrorSystemClass => _mirrorSystemClass ??=
+      _findClass(mirrorsLibrary, 'MirrorSystem', required: false);
 
   /// Whether [element] is `MirrorClass.getName`. Used to check for the use of
   /// that static method without forcing the resolution of the `MirrorSystem`
   /// class until it is necessary.
-  bool isMirrorSystemGetNameFunction(MemberEntity element);
+  FunctionEntity _mirrorSystemGetNameFunction;
+  bool isMirrorSystemGetNameFunction(MemberEntity element) {
+    if (_mirrorSystemGetNameFunction == null) {
+      if (!element.isFunction || mirrorsLibrary == null) return false;
+      ClassEntity cls = mirrorSystemClass;
+      if (element.enclosingClass != cls) return false;
+      if (cls != null) {
+        _mirrorSystemGetNameFunction =
+            _findClassMember(cls, 'getName', required: false);
+      }
+    }
+    return element == _mirrorSystemGetNameFunction;
+  }
 
   /// The `MirrorsUsed` annotation in dart:mirrors.
-  ClassEntity get mirrorsUsedClass;
+  ClassEntity _mirrorsUsedClass;
+  ClassEntity get mirrorsUsedClass => _mirrorsUsedClass ??=
+      _findClass(mirrorsLibrary, 'MirrorsUsed', required: false);
 
   /// Whether [element] is the constructor of the `MirrorsUsed` class. Used to
   /// check for the constructor without forcing the resolution of the
   /// `MirrorsUsed` class until it is necessary.
-  bool isMirrorsUsedConstructor(ConstructorEntity element);
+  bool isMirrorsUsedConstructor(ConstructorEntity element) =>
+      mirrorsLibrary != null && mirrorsUsedClass == element.enclosingClass;
 
   /// The `DeferredLibrary` annotation in dart:async that was used before the
   /// deferred import syntax was introduced.
   // TODO(sigmund): drop support for this old syntax?
-  ClassEntity get deferredLibraryClass;
+  ClassEntity _deferredLibraryClass;
+  ClassEntity get deferredLibraryClass =>
+      _deferredLibraryClass ??= _findClass(asyncLibrary, "DeferredLibrary");
 
   /// The function `identical` in dart:core.
-  FunctionEntity get identicalFunction;
+  FunctionEntity _identicalFunction;
+  FunctionEntity get identicalFunction =>
+      _identicalFunction ??= _findLibraryMember(coreLibrary, 'identical');
 
   /// The method `Function.apply`.
-  FunctionEntity get functionApplyMethod;
+  FunctionEntity _functionApplyMethod;
+  FunctionEntity get functionApplyMethod =>
+      _functionApplyMethod ??= _findClassMember(functionClass, 'apply');
 
   /// Whether [element] is the same as [functionApplyMethod]. This will not
   /// resolve the apply method if it hasn't been seen yet during compilation.
-  bool isFunctionApplyMethod(MemberEntity element);
+  bool isFunctionApplyMethod(MemberEntity element) =>
+      element.name == 'apply' && element.enclosingClass == functionClass;
 
   /// Returns `true` if [element] is the unnamed constructor of `List`. This
   /// will not resolve the constructor if it hasn't been seen yet during
   /// compilation.
-  bool isUnnamedListConstructor(ConstructorEntity element);
+  bool isUnnamedListConstructor(ConstructorEntity element) =>
+      element.name == '' && element.enclosingClass == listClass;
 
   /// Returns `true` if [element] is the 'filled' constructor of `List`. This
   /// will not resolve the constructor if it hasn't been seen yet during
   /// compilation.
-  bool isFilledListConstructor(ConstructorEntity element);
+  bool isFilledListConstructor(ConstructorEntity element) =>
+      element.name == 'filled' && element.enclosingClass == listClass;
 
   /// The `dynamic` type.
-  DynamicType get dynamicType;
+  DynamicType get dynamicType => _env.dynamicType;
 
   /// The `Object` type defined in 'dart:core'.
-  InterfaceType get objectType;
+  InterfaceType get objectType => _getRawType(objectClass);
 
   /// The `bool` type defined in 'dart:core'.
-  InterfaceType get boolType;
+  InterfaceType get boolType => _getRawType(boolClass);
 
   /// The `num` type defined in 'dart:core'.
-  InterfaceType get numType;
+  InterfaceType get numType => _getRawType(numClass);
 
   /// The `int` type defined in 'dart:core'.
-  InterfaceType get intType;
+  InterfaceType get intType => _getRawType(intClass);
 
   /// The `double` type defined in 'dart:core'.
-  InterfaceType get doubleType;
+  InterfaceType get doubleType => _getRawType(doubleClass);
 
   /// The `Resource` type defined in 'dart:core'.
-  InterfaceType get resourceType;
+  InterfaceType get resourceType => _getRawType(resourceClass);
 
   /// The `String` type defined in 'dart:core'.
-  InterfaceType get stringType;
+  InterfaceType get stringType => _getRawType(stringClass);
 
   /// The `Symbol` type defined in 'dart:core'.
-  InterfaceType get symbolType;
+  InterfaceType get symbolType => _getRawType(symbolClass);
 
   /// The `Function` type defined in 'dart:core'.
-  InterfaceType get functionType;
+  InterfaceType get functionType => _getRawType(functionClass);
 
   /// The `Null` type defined in 'dart:core'.
-  InterfaceType get nullType;
+  InterfaceType get nullType => _getRawType(nullClass);
 
   /// The `Type` type defined in 'dart:core'.
-  InterfaceType get typeType;
+  InterfaceType get typeType => _getRawType(typeClass);
 
   /// The `StackTrace` type defined in 'dart:core';
-  InterfaceType get stackTraceType;
+  InterfaceType get stackTraceType => _getRawType(stackTraceClass);
 
   /// Returns an instance of the `List` type defined in 'dart:core' with
   /// [elementType] as its type argument.
   ///
   /// If no type argument is provided, the canonical raw type is returned.
-  InterfaceType listType([DartType elementType]);
+  InterfaceType listType([DartType elementType]) {
+    if (elementType == null) {
+      return _getRawType(listClass);
+    }
+    return _createInterfaceType(listClass, [elementType]);
+  }
 
   /// Returns an instance of the `Map` type defined in 'dart:core' with
   /// [keyType] and [valueType] as its type arguments.
   ///
   /// If no type arguments are provided, the canonical raw type is returned.
-  InterfaceType mapType([DartType keyType, DartType valueType]);
+  InterfaceType mapType([DartType keyType, DartType valueType]) {
+    if (keyType == null && valueType == null) {
+      return _getRawType(mapClass);
+    } else if (keyType == null) {
+      keyType = dynamicType;
+    } else if (valueType == null) {
+      valueType = dynamicType;
+    }
+    return _createInterfaceType(mapClass, [keyType, valueType]);
+  }
 
   /// Returns an instance of the `Iterable` type defined in 'dart:core' with
   /// [elementType] as its type argument.
   ///
   /// If no type argument is provided, the canonical raw type is returned.
-  InterfaceType iterableType([DartType elementType]);
+  InterfaceType iterableType([DartType elementType]) {
+    if (elementType == null) {
+      return _getRawType(iterableClass);
+    }
+    return _createInterfaceType(iterableClass, [elementType]);
+  }
 
   /// Returns an instance of the `Future` type defined in 'dart:async' with
   /// [elementType] as its type argument.
   ///
   /// If no type argument is provided, the canonical raw type is returned.
-  InterfaceType futureType([DartType elementType]);
+  InterfaceType futureType([DartType elementType]) {
+    if (elementType == null) {
+      return _getRawType(futureClass);
+    }
+    return _createInterfaceType(futureClass, [elementType]);
+  }
 
   /// Returns an instance of the `Stream` type defined in 'dart:async' with
   /// [elementType] as its type argument.
   ///
   /// If no type argument is provided, the canonical raw type is returned.
-  InterfaceType streamType([DartType elementType]);
+  InterfaceType streamType([DartType elementType]) {
+    if (elementType == null) {
+      return _getRawType(streamClass);
+    }
+    return _createInterfaceType(streamClass, [elementType]);
+  }
 
   /// Returns `true` if [element] is a superclass of `String` or `num`.
-  bool isNumberOrStringSupertype(ClassEntity element);
+  // TODO(johnniwinther): Change types to `ClassEntity` when these are not
+  // called with unrelated elements.
+  bool isNumberOrStringSupertype(/*Class*/ Entity element) {
+    return element == _findClass(coreLibrary, 'Comparable', required: false);
+  }
 
   /// Returns `true` if [element] is a superclass of `String`.
-  bool isStringOnlySupertype(ClassEntity element);
+  // TODO(johnniwinther): Change types to `ClassEntity` when these are not
+  // called with unrelated elements.
+  bool isStringOnlySupertype(/*Class*/ Entity element) {
+    return element == _findClass(coreLibrary, 'Pattern', required: false);
+  }
 
   /// Returns `true` if [element] is a superclass of `List`.
-  bool isListSupertype(ClassEntity element);
+  bool isListSupertype(ClassEntity element) => element == iterableClass;
 }
 
 /// Interface for accessing libraries, classes and members.
@@ -305,273 +437,800 @@ class CommonElementsImpl implements CommonElements {
 
   CommonElementsImpl(this._env);
 
-  ClassEntity findClass(LibraryEntity library, String name,
+  ClassEntity _findClass(LibraryEntity library, String name,
       {bool required: true}) {
     if (library == null) return null;
     return _env.lookupClass(library, name, required: required);
   }
 
-  MemberEntity findLibraryMember(LibraryEntity library, String name,
+  MemberEntity _findLibraryMember(LibraryEntity library, String name,
       {bool setter: false, bool required: true}) {
     if (library == null) return null;
     return _env.lookupLibraryMember(library, name,
         setter: setter, required: required);
   }
 
-  MemberEntity findClassMember(ClassEntity cls, String name,
+  MemberEntity _findClassMember(ClassEntity cls, String name,
       {bool setter: false, bool required: true}) {
     return _env.lookupClassMember(cls, name,
         setter: setter, required: required);
   }
 
-  ConstructorEntity findConstructor(ClassEntity cls, String name,
+  ConstructorEntity _findConstructor(ClassEntity cls, String name,
       {bool required: true}) {
     return _env.lookupConstructor(cls, name, required: required);
   }
 
-  DartType get dynamicType => _env.dynamicType;
-
   /// Return the raw type of [cls].
-  InterfaceType getRawType(ClassEntity cls) {
+  InterfaceType _getRawType(ClassEntity cls) {
     return _env.getRawType(cls);
   }
 
   /// Create the instantiation of [cls] with the given [typeArguments].
-  InterfaceType createInterfaceType(
+  InterfaceType _createInterfaceType(
       ClassEntity cls, List<DartType> typeArguments) {
     return _env.createInterfaceType(cls, typeArguments);
   }
 
-  LibraryEntity _coreLibrary;
-  LibraryEntity get coreLibrary =>
-      _coreLibrary ??= _env.lookupLibrary(Uris.dart_core, required: true);
-
-  LibraryEntity _typedDataLibrary;
-  LibraryEntity get typedDataLibrary =>
-      _typedDataLibrary ??= _env.lookupLibrary(Uris.dart__native_typed_data);
-
-  LibraryEntity _mirrorsLibrary;
-  LibraryEntity get mirrorsLibrary =>
-      _mirrorsLibrary ??= _env.lookupLibrary(Uris.dart_mirrors);
-
-  LibraryEntity _asyncLibrary;
-  LibraryEntity get asyncLibrary =>
-      _asyncLibrary ??= _env.lookupLibrary(Uris.dart_async);
-
   // From dart:core
+  FunctionEntity get malformedTypeError =>
+      _cachedCoreHelper('_malformedTypeError');
+  FunctionEntity get genericNoSuchMethod =>
+      _cachedCoreHelper('_genericNoSuchMethod');
+  FunctionEntity get unresolvedConstructorError =>
+      _cachedCoreHelper('_unresolvedConstructorError');
+  FunctionEntity get unresolvedStaticGetterError =>
+      _cachedCoreHelper('_unresolvedStaticGetterError');
+  FunctionEntity get unresolvedStaticSetterError =>
+      _cachedCoreHelper('_unresolvedStaticSetterError');
+  FunctionEntity get unresolvedStaticMethodError =>
+      _cachedCoreHelper('_unresolvedStaticMethodError');
+  FunctionEntity get unresolvedTopLevelGetterError =>
+      _cachedCoreHelper('_unresolvedTopLevelGetterError');
+  FunctionEntity get unresolvedTopLevelSetterError =>
+      _cachedCoreHelper('_unresolvedTopLevelSetterError');
+  FunctionEntity get unresolvedTopLevelMethodError =>
+      _cachedCoreHelper('_unresolvedTopLevelMethodError');
+
+  Map<String, FunctionEntity> _cachedCoreHelpers = <String, FunctionEntity>{};
+  FunctionEntity _cachedCoreHelper(String name) => _cachedCoreHelpers[name] ??=
+      _env.lookupLibraryMember(coreLibrary, name, required: true);
+
+  FunctionEntity _objectEquals;
+  FunctionEntity get objectEquals =>
+      _objectEquals ??= _findClassMember(objectClass, '==');
+
+  ClassEntity _mapLiteralClass;
+  ClassEntity get mapLiteralClass {
+    if (_mapLiteralClass == null) {
+      _mapLiteralClass = _env.lookupClass(coreLibrary, 'LinkedHashMap');
+      if (_mapLiteralClass == null) {
+        _mapLiteralClass = _findClass(
+            _env.lookupLibrary(Uris.dart_collection), 'LinkedHashMap');
+      }
+    }
+    return _mapLiteralClass;
+  }
 
-  ClassEntity _objectClass;
-  ClassEntity get objectClass =>
-      _objectClass ??= findClass(coreLibrary, 'Object');
+  ConstructorEntity _mapLiteralConstructor;
+  ConstructorEntity _mapLiteralConstructorEmpty;
+  FunctionEntity _mapLiteralUntypedMaker;
+  FunctionEntity _mapLiteralUntypedEmptyMaker;
+  void _ensureMapLiteralHelpers() {
+    if (_mapLiteralConstructor != null) return;
+
+    _mapLiteralConstructor =
+        _env.lookupConstructor(mapLiteralClass, '_literal');
+    _mapLiteralConstructorEmpty =
+        _env.lookupConstructor(mapLiteralClass, '_empty');
+    _mapLiteralUntypedMaker =
+        _env.lookupClassMember(mapLiteralClass, '_makeLiteral');
+    _mapLiteralUntypedEmptyMaker =
+        _env.lookupClassMember(mapLiteralClass, '_makeEmpty');
+  }
 
-  ClassEntity _boolClass;
-  ClassEntity get boolClass => _boolClass ??= findClass(coreLibrary, 'bool');
+  ConstructorEntity get mapLiteralConstructor {
+    _ensureMapLiteralHelpers();
+    return _mapLiteralConstructor;
+  }
 
-  ClassEntity _numClass;
-  ClassEntity get numClass => _numClass ??= findClass(coreLibrary, 'num');
+  ConstructorEntity get mapLiteralConstructorEmpty {
+    _ensureMapLiteralHelpers();
+    return _mapLiteralConstructorEmpty;
+  }
 
-  ClassEntity _intClass;
-  ClassEntity get intClass => _intClass ??= findClass(coreLibrary, 'int');
+  FunctionEntity get mapLiteralUntypedMaker {
+    _ensureMapLiteralHelpers();
+    return _mapLiteralUntypedMaker;
+  }
 
-  ClassEntity _doubleClass;
-  ClassEntity get doubleClass =>
-      _doubleClass ??= findClass(coreLibrary, 'double');
+  FunctionEntity get mapLiteralUntypedEmptyMaker {
+    _ensureMapLiteralHelpers();
+    return _mapLiteralUntypedEmptyMaker;
+  }
 
-  ClassEntity _stringClass;
-  ClassEntity get stringClass =>
-      _stringClass ??= findClass(coreLibrary, 'String');
+  FunctionEntity _objectNoSuchMethod;
+  FunctionEntity get objectNoSuchMethod {
+    return _objectNoSuchMethod ??=
+        _env.lookupClassMember(objectClass, Identifiers.noSuchMethod_);
+  }
 
-  ClassEntity _functionClass;
-  ClassEntity get functionClass =>
-      _functionClass ??= findClass(coreLibrary, 'Function');
+  bool isDefaultNoSuchMethodImplementation(FunctionEntity element) {
+    ClassEntity classElement = element.enclosingClass;
+    return classElement == objectClass ||
+        classElement == jsInterceptorClass ||
+        classElement == jsNullClass;
+  }
 
-  FunctionEntity _functionApplyMethod;
-  FunctionEntity get functionApplyMethod =>
-      _functionApplyMethod ??= findClassMember(functionClass, 'apply');
+  // From dart:async
+  ClassEntity _findAsyncHelperClass(String name) =>
+      _findClass(asyncLibrary, name);
 
-  bool isFunctionApplyMethod(MemberEntity element) =>
-      element.name == 'apply' && element.enclosingClass == functionClass;
+  FunctionEntity _findAsyncHelperFunction(String name) =>
+      _findLibraryMember(asyncLibrary, name);
 
-  ClassEntity _nullClass;
-  ClassEntity get nullClass => _nullClass ??= findClass(coreLibrary, 'Null');
+  FunctionEntity get asyncHelper => _findAsyncHelperFunction("_asyncHelper");
 
-  ClassEntity _listClass;
-  ClassEntity get listClass => _listClass ??= findClass(coreLibrary, 'List');
+  FunctionEntity get wrapBody =>
+      _findAsyncHelperFunction("_wrapJsFunctionForAsync");
 
-  ClassEntity _typeClass;
-  ClassEntity get typeClass => _typeClass ??= findClass(coreLibrary, 'Type');
+  FunctionEntity get yieldStar => _env.lookupClassMember(
+      _findAsyncHelperClass("_IterationMarker"), "yieldStar");
 
-  ClassEntity _mapClass;
-  ClassEntity get mapClass => _mapClass ??= findClass(coreLibrary, 'Map');
+  FunctionEntity get yieldSingle => _env.lookupClassMember(
+      _findAsyncHelperClass("_IterationMarker"), "yieldSingle");
 
-  ClassEntity _symbolClass;
-  ClassEntity get symbolClass =>
-      _symbolClass ??= findClass(coreLibrary, 'Symbol');
+  FunctionEntity get syncStarUncaughtError => _env.lookupClassMember(
+      _findAsyncHelperClass("_IterationMarker"), "uncaughtError");
 
-  ConstructorEntity _symbolConstructor;
-  ConstructorEntity get symbolConstructor =>
-      _symbolConstructor ??= findConstructor(symbolClass, '');
+  FunctionEntity get asyncStarHelper =>
+      _findAsyncHelperFunction("_asyncStarHelper");
 
-  bool isSymbolConstructor(Entity e) => e == symbolConstructor;
+  FunctionEntity get streamOfController =>
+      _findAsyncHelperFunction("_streamOfController");
 
-  ClassEntity _stackTraceClass;
-  ClassEntity get stackTraceClass =>
-      _stackTraceClass ??= findClass(coreLibrary, 'StackTrace');
+  FunctionEntity get endOfIteration => _env.lookupClassMember(
+      _findAsyncHelperClass("_IterationMarker"), "endOfIteration");
 
-  ClassEntity _iterableClass;
-  ClassEntity get iterableClass =>
-      _iterableClass ??= findClass(coreLibrary, 'Iterable');
+  ClassEntity get syncStarIterable =>
+      _findAsyncHelperClass("_SyncStarIterable");
 
-  ClassEntity _resourceClass;
-  ClassEntity get resourceClass =>
-      _resourceClass ??= findClass(coreLibrary, 'Resource');
+  ClassEntity get futureImplementation => _findAsyncHelperClass('_Future');
 
-  FunctionEntity _identicalFunction;
-  FunctionEntity get identicalFunction =>
-      _identicalFunction ??= findLibraryMember(coreLibrary, 'identical');
+  ClassEntity get controllerStream =>
+      _findAsyncHelperClass("_ControllerStream");
 
-  // From dart:async
+  ConstructorEntity get syncStarIterableConstructor =>
+      _env.lookupConstructor(syncStarIterable, "");
 
-  ClassEntity _futureClass;
-  ClassEntity get futureClass =>
-      _futureClass ??= findClass(asyncLibrary, 'Future');
+  ConstructorEntity get syncCompleterConstructor =>
+      _env.lookupConstructor(_findAsyncHelperClass("Completer"), "sync");
 
-  ClassEntity _streamClass;
-  ClassEntity get streamClass =>
-      _streamClass ??= findClass(asyncLibrary, 'Stream');
+  ClassEntity get asyncStarController =>
+      _findAsyncHelperClass("_AsyncStarStreamController");
 
-  ClassEntity _deferredLibraryClass;
-  ClassEntity get deferredLibraryClass =>
-      _deferredLibraryClass ??= findClass(asyncLibrary, "DeferredLibrary");
+  ConstructorEntity get asyncStarControllerConstructor =>
+      _env.lookupConstructor(asyncStarController, "", required: true);
 
-  // From dart:mirrors
+  ConstructorEntity get streamIteratorConstructor =>
+      _env.lookupConstructor(_findAsyncHelperClass("StreamIterator"), "");
 
-  ClassEntity _mirrorSystemClass;
-  ClassEntity get mirrorSystemClass => _mirrorSystemClass ??=
-      findClass(mirrorsLibrary, 'MirrorSystem', required: false);
+  // From dart:mirrors
+  FunctionEntity _findMirrorsFunction(String name) {
+    LibraryEntity library = _env.lookupLibrary(Uris.dart__js_mirrors);
+    if (library == null) return null;
+    return _env.lookupLibraryMember(library, name, required: true);
+  }
 
-  FunctionEntity _mirrorSystemGetNameFunction;
-  bool isMirrorSystemGetNameFunction(MemberEntity element) {
-    if (_mirrorSystemGetNameFunction == null) {
-      if (!element.isFunction || mirrorsLibrary == null) return false;
-      ClassEntity cls = mirrorSystemClass;
-      if (element.enclosingClass != cls) return false;
-      if (cls != null) {
-        _mirrorSystemGetNameFunction =
-            findClassMember(cls, 'getName', required: false);
+  /// Holds the method "disableTreeShaking" in js_mirrors when
+  /// dart:mirrors has been loaded.
+  FunctionEntity _disableTreeShakingMarker;
+  FunctionEntity get disableTreeShakingMarker =>
+      _disableTreeShakingMarker ??= _findMirrorsFunction('disableTreeShaking');
+
+  /// Holds the method "preserveNames" in js_mirrors when
+  /// dart:mirrors has been loaded.
+  FunctionEntity _preserveNamesMarker;
+  FunctionEntity get preserveNamesMarker {
+    if (_preserveNamesMarker == null) {
+      LibraryEntity library = _env.lookupLibrary(Uris.dart__js_names);
+      if (library != null) {
+        _preserveNamesMarker = _findLibraryMember(library, 'preserveNames');
       }
     }
-    return element == _mirrorSystemGetNameFunction;
+    return _preserveNamesMarker;
   }
 
-  ClassEntity _mirrorsUsedClass;
-  ClassEntity get mirrorsUsedClass => _mirrorsUsedClass ??=
-      findClass(mirrorsLibrary, 'MirrorsUsed', required: false);
+  /// Holds the method "preserveMetadata" in js_mirrors when
+  /// dart:mirrors has been loaded.
+  FunctionEntity _preserveMetadataMarker;
+  FunctionEntity get preserveMetadataMarker =>
+      _preserveMetadataMarker ??= _findMirrorsFunction('preserveMetadata');
+
+  /// Holds the method "preserveUris" in js_mirrors when
+  /// dart:mirrors has been loaded.
+  FunctionEntity _preserveUrisMarker;
+  FunctionEntity get preserveUrisMarker =>
+      _preserveUrisMarker ??= _findMirrorsFunction('preserveUris');
+
+  /// Holds the method "preserveLibraryNames" in js_mirrors when
+  /// dart:mirrors has been loaded.
+  FunctionEntity _preserveLibraryNamesMarker;
+  FunctionEntity get preserveLibraryNamesMarker =>
+      _preserveLibraryNamesMarker ??=
+          _findMirrorsFunction('preserveLibraryNames');
+
+  // From dart:_interceptors
+  ClassEntity _findInterceptorsClass(String name) =>
+      _findClass(interceptorsLibrary, name);
+
+  FunctionEntity _findInterceptorsFunction(String name) =>
+      _findLibraryMember(interceptorsLibrary, name);
+
+  ClassEntity _jsInterceptorClass;
+  ClassEntity get jsInterceptorClass =>
+      _jsInterceptorClass ??= _findInterceptorsClass('Interceptor');
+
+  ClassEntity _jsStringClass;
+  ClassEntity get jsStringClass =>
+      _jsStringClass ??= _findInterceptorsClass('JSString');
+
+  ClassEntity _jsArrayClass;
+  ClassEntity get jsArrayClass =>
+      _jsArrayClass ??= _findInterceptorsClass('JSArray');
+
+  ClassEntity _jsNumberClass;
+  ClassEntity get jsNumberClass =>
+      _jsNumberClass ??= _findInterceptorsClass('JSNumber');
+
+  ClassEntity _jsIntClass;
+  ClassEntity get jsIntClass => _jsIntClass ??= _findInterceptorsClass('JSInt');
+
+  ClassEntity _jsDoubleClass;
+  ClassEntity get jsDoubleClass =>
+      _jsDoubleClass ??= _findInterceptorsClass('JSDouble');
+
+  ClassEntity _jsNullClass;
+  ClassEntity get jsNullClass =>
+      _jsNullClass ??= _findInterceptorsClass('JSNull');
+
+  ClassEntity _jsBoolClass;
+  ClassEntity get jsBoolClass =>
+      _jsBoolClass ??= _findInterceptorsClass('JSBool');
+
+  ClassEntity _jsPlainJavaScriptObjectClass;
+  ClassEntity get jsPlainJavaScriptObjectClass =>
+      _jsPlainJavaScriptObjectClass ??=
+          _findInterceptorsClass('PlainJavaScriptObject');
+
+  ClassEntity _jsUnknownJavaScriptObjectClass;
+  ClassEntity get jsUnknownJavaScriptObjectClass =>
+      _jsUnknownJavaScriptObjectClass ??=
+          _findInterceptorsClass('UnknownJavaScriptObject');
+
+  ClassEntity _jsJavaScriptFunctionClass;
+  ClassEntity get jsJavaScriptFunctionClass => _jsJavaScriptFunctionClass ??=
+      _findInterceptorsClass('JavaScriptFunction');
+
+  ClassEntity _jsJavaScriptObjectClass;
+  ClassEntity get jsJavaScriptObjectClass =>
+      _jsJavaScriptObjectClass ??= _findInterceptorsClass('JavaScriptObject');
+
+  ClassEntity _jsIndexableClass;
+  ClassEntity get jsIndexableClass =>
+      _jsIndexableClass ??= _findInterceptorsClass('JSIndexable');
+
+  ClassEntity _jsMutableIndexableClass;
+  ClassEntity get jsMutableIndexableClass =>
+      _jsMutableIndexableClass ??= _findInterceptorsClass('JSMutableIndexable');
+
+  ClassEntity _jsMutableArrayClass;
+  ClassEntity get jsMutableArrayClass =>
+      _jsMutableArrayClass ??= _findInterceptorsClass('JSMutableArray');
+
+  ClassEntity _jsFixedArrayClass;
+  ClassEntity get jsFixedArrayClass =>
+      _jsFixedArrayClass ??= _findInterceptorsClass('JSFixedArray');
+
+  ClassEntity _jsExtendableArrayClass;
+  ClassEntity get jsExtendableArrayClass =>
+      _jsExtendableArrayClass ??= _findInterceptorsClass('JSExtendableArray');
+
+  ClassEntity _jsUnmodifiableArrayClass;
+  ClassEntity get jsUnmodifiableArrayClass => _jsUnmodifiableArrayClass ??=
+      _findInterceptorsClass('JSUnmodifiableArray');
+
+  ClassEntity _jsPositiveIntClass;
+  ClassEntity get jsPositiveIntClass =>
+      _jsPositiveIntClass ??= _findInterceptorsClass('JSPositiveInt');
+
+  ClassEntity _jsUInt32Class;
+  ClassEntity get jsUInt32Class =>
+      _jsUInt32Class ??= _findInterceptorsClass('JSUInt32');
+
+  ClassEntity _jsUInt31Class;
+  ClassEntity get jsUInt31Class =>
+      _jsUInt31Class ??= _findInterceptorsClass('JSUInt31');
+
+  FunctionEntity _findIndexForNativeSubclassType;
+  FunctionEntity get findIndexForNativeSubclassType =>
+      _findIndexForNativeSubclassType ??= _findLibraryMember(
+          interceptorsLibrary, 'findIndexForNativeSubclassType');
+
+  FunctionEntity _getInterceptorMethod;
+  FunctionEntity get getInterceptorMethod =>
+      _getInterceptorMethod ??= _findInterceptorsFunction('getInterceptor');
+
+  FunctionEntity _getNativeInterceptorMethod;
+  FunctionEntity get getNativeInterceptorMethod =>
+      _getNativeInterceptorMethod ??=
+          _findInterceptorsFunction('getNativeInterceptor');
+
+  MemberEntity _jsIndexableLength;
+  MemberEntity get jsIndexableLength =>
+      _jsIndexableLength ??= _findClassMember(jsIndexableClass, 'length');
+
+  ConstructorEntity _jsArrayTypedConstructor;
+  ConstructorEntity get jsArrayTypedConstructor =>
+      _jsArrayTypedConstructor ??= _findConstructor(jsArrayClass, 'typed');
+
+  FunctionEntity _jsArrayRemoveLast;
+  FunctionEntity get jsArrayRemoveLast =>
+      _jsArrayRemoveLast ??= _findClassMember(jsArrayClass, 'removeLast');
+
+  FunctionEntity _jsArrayAdd;
+  FunctionEntity get jsArrayAdd =>
+      _jsArrayAdd ??= _findClassMember(jsArrayClass, 'add');
+
+  FunctionEntity _jsStringSplit;
+  FunctionEntity get jsStringSplit =>
+      _jsStringSplit ??= _findClassMember(jsStringClass, 'split');
+
+  FunctionEntity _jsStringToString;
+  FunctionEntity get jsStringToString =>
+      _jsStringToString ??= _findClassMember(jsStringClass, 'toString');
+
+  FunctionEntity _jsStringOperatorAdd;
+  FunctionEntity get jsStringOperatorAdd =>
+      _jsStringOperatorAdd ??= _findClassMember(jsStringClass, '+');
+
+  // From package:js
+  ClassEntity _jsAnnotationClass;
+  ClassEntity get jsAnnotationClass {
+    if (_jsAnnotationClass == null) {
+      LibraryEntity library = _env.lookupLibrary(Uris.package_js);
+      if (library == null) return null;
+      _jsAnnotationClass = _findClass(library, 'JS');
+    }
+    return _jsAnnotationClass;
+  }
 
-  bool isMirrorsUsedConstructor(ConstructorEntity element) =>
-      mirrorsLibrary != null && mirrorsUsedClass == element.enclosingClass;
+  ClassEntity _jsAnonymousClass;
+  ClassEntity get jsAnonymousClass {
+    if (_jsAnonymousClass == null) {
+      LibraryEntity library = _env.lookupLibrary(Uris.package_js);
+      if (library == null) return null;
+      _jsAnonymousClass = _findClass(library, '_Anonymous');
+    }
+    return _jsAnonymousClass;
+  }
 
-  // From dart:typed_data
+  // From dart:_js_helper
+  // TODO(johnniwinther): Avoid the need for this (from [CheckedModeHelper]).
+  FunctionEntity findHelperFunction(String name) => _findHelperFunction(name);
 
-  ClassEntity _typedDataClass;
-  ClassEntity get typedDataClass =>
-      _typedDataClass ??= findClass(typedDataLibrary, 'NativeTypedData');
+  FunctionEntity _findHelperFunction(String name) =>
+      _findLibraryMember(jsHelperLibrary, name);
 
-  bool isUnnamedListConstructor(ConstructorEntity element) =>
-      element.name == '' && element.enclosingClass == listClass;
+  ClassEntity _findHelperClass(String name) =>
+      _findClass(jsHelperLibrary, name);
 
-  bool isFilledListConstructor(ConstructorEntity element) =>
-      element.name == 'filled' && element.enclosingClass == listClass;
+  ClassEntity _closureClass;
+  ClassEntity get closureClass => _closureClass ??= _findHelperClass('Closure');
 
-  // TODO(johnniwinther): Change types to `ClassEntity` when these are not
-  // called with unrelated elements.
-  bool isNumberOrStringSupertype(/*Class*/ Entity element) {
-    return element == findClass(coreLibrary, 'Comparable', required: false);
-  }
+  ClassEntity _boundClosureClass;
+  ClassEntity get boundClosureClass =>
+      _boundClosureClass ??= _findHelperClass('BoundClosure');
 
-  bool isStringOnlySupertype(/*Class*/ Entity element) {
-    return element == findClass(coreLibrary, 'Pattern', required: false);
-  }
+  ClassEntity _typeLiteralClass;
+  ClassEntity get typeLiteralClass =>
+      _typeLiteralClass ??= _findHelperClass('TypeImpl');
 
-  bool isListSupertype(/*Class*/ Entity element) => element == iterableClass;
+  ClassEntity _constMapLiteralClass;
+  ClassEntity get constMapLiteralClass =>
+      _constMapLiteralClass ??= _findHelperClass('ConstantMap');
 
-  @override
-  InterfaceType get objectType => getRawType(objectClass);
+  ClassEntity _typeVariableClass;
+  ClassEntity get typeVariableClass =>
+      _typeVariableClass ??= _findHelperClass('TypeVariable');
 
-  @override
-  InterfaceType get boolType => getRawType(boolClass);
+  ClassEntity _noSideEffectsClass;
+  ClassEntity get noSideEffectsClass =>
+      _noSideEffectsClass ??= _findHelperClass('NoSideEffects');
 
-  @override
-  InterfaceType get doubleType => getRawType(doubleClass);
+  ClassEntity _noThrowsClass;
+  ClassEntity get noThrowsClass =>
+      _noThrowsClass ??= _findHelperClass('NoThrows');
 
-  @override
-  InterfaceType get functionType => getRawType(functionClass);
+  ClassEntity _noInlineClass;
+  ClassEntity get noInlineClass =>
+      _noInlineClass ??= _findHelperClass('NoInline');
 
-  @override
-  InterfaceType get intType => getRawType(intClass);
+  ClassEntity _forceInlineClass;
+  ClassEntity get forceInlineClass =>
+      _forceInlineClass ??= _findHelperClass('ForceInline');
 
-  @override
-  InterfaceType get resourceType => getRawType(resourceClass);
+  ClassEntity _irRepresentationClass;
+  ClassEntity get irRepresentationClass =>
+      _irRepresentationClass ??= _findHelperClass('IrRepresentation');
 
-  @override
-  InterfaceType listType([DartType elementType]) {
-    if (elementType == null) {
-      return getRawType(listClass);
-    }
-    return createInterfaceType(listClass, [elementType]);
-  }
+  ClassEntity _jsInvocationMirrorClass;
+  ClassEntity get jsInvocationMirrorClass =>
+      _jsInvocationMirrorClass ??= _findHelperClass('JSInvocationMirror');
 
-  @override
-  InterfaceType mapType([DartType keyType, DartType valueType]) {
-    if (keyType == null && valueType == null) {
-      return getRawType(mapClass);
-    } else if (keyType == null) {
-      keyType = dynamicType;
-    } else if (valueType == null) {
-      valueType = dynamicType;
-    }
-    return createInterfaceType(mapClass, [keyType, valueType]);
-  }
+  /// Interface used to determine if an object has the JavaScript
+  /// indexing behavior. The interface is only visible to specific libraries.
+  ClassEntity _jsIndexingBehaviorInterface;
+  ClassEntity get jsIndexingBehaviorInterface =>
+      _jsIndexingBehaviorInterface ??=
+          _findHelperClass('JavaScriptIndexingBehavior');
 
-  @override
-  InterfaceType get nullType => getRawType(nullClass);
+  ClassEntity get VoidRuntimeType => _findHelperClass('VoidRuntimeType');
 
-  @override
-  InterfaceType get numType => getRawType(numClass);
+  ClassEntity get stackTraceHelperClass => _findHelperClass('_StackTrace');
 
-  @override
-  InterfaceType get stringType => getRawType(stringClass);
+  ClassEntity get constantMapClass =>
+      _findHelperClass(JavaScriptMapConstant.DART_CLASS);
+  ClassEntity get constantStringMapClass =>
+      _findHelperClass(JavaScriptMapConstant.DART_STRING_CLASS);
+  ClassEntity get constantProtoMapClass =>
+      _findHelperClass(JavaScriptMapConstant.DART_PROTO_CLASS);
+  ClassEntity get generalConstantMapClass =>
+      _findHelperClass(JavaScriptMapConstant.DART_GENERAL_CLASS);
 
-  @override
-  InterfaceType get symbolType => getRawType(symbolClass);
+  ClassEntity get annotationCreatesClass => _findHelperClass('Creates');
 
-  @override
-  InterfaceType get typeType => getRawType(typeClass);
+  ClassEntity get annotationReturnsClass => _findHelperClass('Returns');
 
-  @override
-  InterfaceType get stackTraceType => getRawType(stackTraceClass);
+  ClassEntity get annotationJSNameClass => _findHelperClass('JSName');
 
-  @override
-  InterfaceType iterableType([DartType elementType]) {
-    if (elementType == null) {
-      return getRawType(iterableClass);
-    }
-    return createInterfaceType(iterableClass, [elementType]);
-  }
+  /// The class for patch annotations defined in dart:_js_helper.
+  ClassEntity _patchAnnotationClass;
+  ClassEntity get patchAnnotationClass =>
+      _patchAnnotationClass ??= _findHelperClass('_Patch');
 
-  @override
-  InterfaceType futureType([DartType elementType]) {
-    if (elementType == null) {
-      return getRawType(futureClass);
-    }
-    return createInterfaceType(futureClass, [elementType]);
+  /// The class for native annotations defined in dart:_js_helper.
+  ClassEntity _nativeAnnotationClass;
+  ClassEntity get nativeAnnotationClass =>
+      _nativeAnnotationClass ??= _findHelperClass('Native');
+
+  ConstructorEntity _typeVariableConstructor;
+  ConstructorEntity get typeVariableConstructor => _typeVariableConstructor ??=
+      _env.lookupConstructor(typeVariableClass, '');
+
+  FunctionEntity _invokeOnMethod;
+  FunctionEntity get invokeOnMethod => _invokeOnMethod ??=
+      _env.lookupClassMember(jsInvocationMirrorClass, '_getCachedInvocation');
+
+  FunctionEntity _assertTest;
+  FunctionEntity get assertTest =>
+      _assertTest ??= _findHelperFunction('assertTest');
+
+  FunctionEntity _assertThrow;
+  FunctionEntity get assertThrow =>
+      _assertThrow ??= _findHelperFunction('assertThrow');
+
+  FunctionEntity _assertHelper;
+  FunctionEntity get assertHelper =>
+      _assertHelper ??= _findHelperFunction('assertHelper');
+
+  FunctionEntity _assertUnreachableMethod;
+  FunctionEntity get assertUnreachableMethod =>
+      _assertUnreachableMethod ??= _findHelperFunction('assertUnreachable');
+
+  /// Holds the method "getIsolateAffinityTag" when dart:_js_helper has been
+  /// loaded.
+  FunctionEntity _getIsolateAffinityTagMarker;
+  FunctionEntity get getIsolateAffinityTagMarker =>
+      _getIsolateAffinityTagMarker ??=
+          _findHelperFunction('getIsolateAffinityTag');
+
+  /// Holds the method "requiresPreamble" in _js_helper.
+  FunctionEntity _requiresPreambleMarker;
+  FunctionEntity get requiresPreambleMarker =>
+      _requiresPreambleMarker ??= _findHelperFunction('requiresPreamble');
+
+  FunctionEntity get badMain => _findHelperFunction('badMain');
+
+  FunctionEntity get missingMain => _findHelperFunction('missingMain');
+
+  FunctionEntity get mainHasTooManyParameters =>
+      _findHelperFunction('mainHasTooManyParameters');
+
+  FunctionEntity get loadLibraryWrapper =>
+      _findHelperFunction("_loadLibraryWrapper");
+
+  FunctionEntity get boolConversionCheck =>
+      _findHelperFunction('boolConversionCheck');
+
+  FunctionEntity get _consoleTraceHelper =>
+      _findHelperFunction('consoleTraceHelper');
+
+  FunctionEntity get _postTraceHelper => _findHelperFunction('postTraceHelper');
+
+  FunctionEntity _traceHelper;
+  FunctionEntity get traceHelper {
+    return _traceHelper ??= JavaScriptBackend.TRACE_METHOD == 'console'
+        ? _consoleTraceHelper
+        : _postTraceHelper;
   }
 
-  @override
-  InterfaceType streamType([DartType elementType]) {
-    if (elementType == null) {
-      return getRawType(streamClass);
+  FunctionEntity get closureFromTearOff =>
+      _findHelperFunction('closureFromTearOff');
+
+  FunctionEntity get isJsIndexable => _findHelperFunction('isJsIndexable');
+
+  FunctionEntity get throwIllegalArgumentException =>
+      _findHelperFunction('iae');
+
+  FunctionEntity get throwIndexOutOfRangeException =>
+      _findHelperFunction('ioore');
+
+  FunctionEntity get exceptionUnwrapper =>
+      _findHelperFunction('unwrapException');
+
+  FunctionEntity get throwRuntimeError =>
+      _findHelperFunction('throwRuntimeError');
+
+  FunctionEntity get throwTypeError => _findHelperFunction('throwTypeError');
+
+  FunctionEntity get throwAbstractClassInstantiationError =>
+      _findHelperFunction('throwAbstractClassInstantiationError');
+
+  FunctionEntity _cachedCheckConcurrentModificationError;
+  FunctionEntity get checkConcurrentModificationError =>
+      _cachedCheckConcurrentModificationError ??=
+          _findHelperFunction('checkConcurrentModificationError');
+
+  FunctionEntity get throwConcurrentModificationError =>
+      _findHelperFunction('throwConcurrentModificationError');
+
+  FunctionEntity _checkInt;
+  FunctionEntity get checkInt => _checkInt ??= _findHelperFunction('checkInt');
+
+  FunctionEntity _checkNum;
+  FunctionEntity get checkNum => _checkNum ??= _findHelperFunction('checkNum');
+
+  FunctionEntity _checkString;
+  FunctionEntity get checkString =>
+      _checkString ??= _findHelperFunction('checkString');
+
+  FunctionEntity get stringInterpolationHelper => _findHelperFunction('S');
+
+  FunctionEntity get wrapExceptionHelper =>
+      _findHelperFunction('wrapException');
+
+  FunctionEntity get throwExpressionHelper =>
+      _findHelperFunction('throwExpression');
+
+  FunctionEntity get closureConverter =>
+      _findHelperFunction('convertDartClosureToJS');
+
+  FunctionEntity get traceFromException =>
+      _findHelperFunction('getTraceFromException');
+
+  FunctionEntity get setRuntimeTypeInfo =>
+      _findHelperFunction('setRuntimeTypeInfo');
+
+  FunctionEntity get getRuntimeTypeInfo =>
+      _findHelperFunction('getRuntimeTypeInfo');
+
+  FunctionEntity get getTypeArgumentByIndex =>
+      _findHelperFunction('getTypeArgumentByIndex');
+
+  FunctionEntity get computeSignature =>
+      _findHelperFunction('computeSignature');
+
+  FunctionEntity get getRuntimeTypeArguments =>
+      _findHelperFunction('getRuntimeTypeArguments');
+
+  FunctionEntity get getRuntimeTypeArgument =>
+      _findHelperFunction('getRuntimeTypeArgument');
+
+  FunctionEntity get runtimeTypeToString =>
+      _findHelperFunction('runtimeTypeToString');
+
+  FunctionEntity get assertIsSubtype => _findHelperFunction('assertIsSubtype');
+
+  FunctionEntity get checkSubtype => _findHelperFunction('checkSubtype');
+
+  FunctionEntity get assertSubtype => _findHelperFunction('assertSubtype');
+
+  FunctionEntity get subtypeCast => _findHelperFunction('subtypeCast');
+
+  FunctionEntity get functionTypeTest =>
+      _findHelperFunction('functionTypeTest');
+
+  FunctionEntity get checkSubtypeOfRuntimeType =>
+      _findHelperFunction('checkSubtypeOfRuntimeType');
+
+  FunctionEntity get assertSubtypeOfRuntimeType =>
+      _findHelperFunction('assertSubtypeOfRuntimeType');
+
+  FunctionEntity get subtypeOfRuntimeTypeCast =>
+      _findHelperFunction('subtypeOfRuntimeTypeCast');
+
+  FunctionEntity get checkDeferredIsLoaded =>
+      _findHelperFunction('checkDeferredIsLoaded');
+
+  FunctionEntity get throwNoSuchMethod =>
+      _findHelperFunction('throwNoSuchMethod');
+
+  FunctionEntity get createRuntimeType =>
+      _findHelperFunction('createRuntimeType');
+
+  FunctionEntity get fallThroughError =>
+      _findHelperFunction("getFallThroughError");
+
+  FunctionEntity get createInvocationMirror =>
+      _findHelperFunction('createInvocationMirror');
+
+  FunctionEntity get cyclicThrowHelper =>
+      _findHelperFunction("throwCyclicInit");
+
+  FunctionEntity get defineProperty => _findHelperFunction('defineProperty');
+
+  FunctionEntity get convertRtiToRuntimeType =>
+      _findHelperFunction('convertRtiToRuntimeType');
+
+  FunctionEntity get toStringForNativeObject =>
+      _findHelperFunction('toStringForNativeObject');
+
+  FunctionEntity get hashCodeForNativeObject =>
+      _findHelperFunction('hashCodeForNativeObject');
+
+  // From dart:_internal
+
+  ClassEntity _symbolImplementationClass;
+  ClassEntity get symbolImplementationClass =>
+      _symbolImplementationClass ??= _findClass(internalLibrary, 'Symbol');
+
+  final Selector symbolValidatedConstructorSelector =
+      new Selector.call(const PublicName('validated'), CallStructure.ONE_ARG);
+
+  ConstructorEntity get symbolValidatedConstructor =>
+      _symbolValidatedConstructor ??= _findConstructor(
+          symbolImplementationClass, symbolValidatedConstructorSelector.name);
+
+  /// Returns the field that holds the internal name in the implementation class
+  /// for `Symbol`.
+  FieldEntity _symbolImplementationField;
+  FieldEntity get symbolImplementationField => _symbolImplementationField ??=
+      _env.lookupClassMember(symbolImplementationClass, '_name',
+          required: true);
+
+  ConstructorEntity _symbolValidatedConstructor;
+  bool isSymbolValidatedConstructor(ConstructorEntity element) {
+    if (_symbolValidatedConstructor != null) {
+      return element == _symbolValidatedConstructor;
     }
-    return createInterfaceType(streamClass, [elementType]);
+    return false;
   }
+
+  // From dart:_native_typed_data
+
+  ClassEntity _typedArrayClass;
+  ClassEntity get typedArrayClass => _typedArrayClass ??= _findClass(
+      _env.lookupLibrary(Uris.dart__native_typed_data, required: true),
+      'NativeTypedArray');
+
+  ClassEntity _typedArrayOfIntClass;
+  ClassEntity get typedArrayOfIntClass => _typedArrayOfIntClass ??= _findClass(
+      _env.lookupLibrary(Uris.dart__native_typed_data, required: true),
+      'NativeTypedArrayOfInt');
+
+  // From dart:_js_embedded_names
+
+  /// Holds the class for the [JsGetName] enum.
+  ClassEntity _jsGetNameEnum;
+  ClassEntity get jsGetNameEnum => _jsGetNameEnum ??= _findClass(
+      _env.lookupLibrary(Uris.dart__js_embedded_names, required: true),
+      'JsGetName');
+
+  /// Holds the class for the [JsBuiltins] enum.
+  ClassEntity _jsBuiltinEnum;
+  ClassEntity get jsBuiltinEnum => _jsBuiltinEnum ??= _findClass(
+      _env.lookupLibrary(Uris.dart__js_embedded_names, required: true),
+      'JsBuiltin');
+
+  // From dart:_isolate_helper
+
+  FunctionEntity get startRootIsolate =>
+      _findLibraryMember(isolateHelperLibrary, 'startRootIsolate');
+
+  FunctionEntity get currentIsolate =>
+      _findLibraryMember(isolateHelperLibrary, '_currentIsolate');
+
+  FunctionEntity get callInIsolate =>
+      _findLibraryMember(isolateHelperLibrary, '_callInIsolate');
+}
+
+/// Interface for accessing libraries, classes and members.
+///
+/// The _env makes private and injected members directly available and
+/// should therefore not be used to determine scopes.
+abstract class ElementEnvironment {

[Johnni Winther, 2017/04/11 09:16:00]

Again, bad merge. [ElementEnvironment] is also declared in line 346.

[Emily Fortuna, 2017/04/11 21:31:35]

fixed up. thanks!

+  /// Returns the main library for the compilation.
+  LibraryEntity get mainLibrary;
+
+  /// Returns the main method for the compilation.
+  FunctionEntity get mainFunction;
+
+  /// Lookup the library with the canonical [uri], fail if the library is
+  /// missing and [required];
+  LibraryEntity lookupLibrary(Uri uri, {bool required: false});
+
+  /// Lookup the class [name] in [library], fail if the class is missing and
+  /// [required].
+  ClassEntity lookupClass(LibraryEntity library, String name,
+      {bool required: false});
+
+  /// Lookup the member [name] in [library], fail if the class is missing and
+  /// [required].
+  MemberEntity lookupLibraryMember(LibraryEntity library, String name,
+      {bool setter: false, bool required: false});
+
+  /// Lookup the member [name] in [cls], fail if the class is missing and
+  /// [required].
+  MemberEntity lookupClassMember(ClassEntity cls, String name,
+      {bool setter: false, bool required: false});
+
+  /// Lookup the constructor [name] in [cls], fail if the class is missing and
+  /// [required].
+  ConstructorEntity lookupConstructor(ClassEntity cls, String name,
+      {bool required: false});
+
+  /// Calls [f] for each class member declared or inherited in [cls] together
+  /// with the class that declared the member.
+  ///
+  /// TODO(johnniwinther): This should not include static members of
+  /// superclasses.
+  void forEachClassMember(
+      ClassEntity cls, void f(ClassEntity declarer, MemberEntity member));
+
+  /// Returns the declared superclass of [cls].
+  ///
+  /// Unnamed mixin applications are skipped, for instance for these classes
+  ///
+  ///     class S {}
+  ///     class M {}
+  ///     class C extends S with M {}
+  ///
+  /// the result of `getSuperClass(C)` is `S` and not the unnamed mixin
+  /// application typically named `S+M`.
+  ClassEntity getSuperClass(ClassEntity cls);
+
+  /// Calls [f] for each class that is mixed into [cls] or one of its
+  /// superclasses.
+  void forEachMixin(ClassEntity cls, void f(ClassEntity mixin));
+
+  /// Create the instantiation of [cls] with the given [typeArguments].
+  InterfaceType createInterfaceType(
+      ClassEntity cls, List<DartType> typeArguments);
+
+  /// Returns the `dynamic` type.
+  // TODO(johnniwinther): Remove this when `ResolutionDynamicType` is no longer
+  // needed.
+  DartType get dynamicType;
+
+  /// Returns the 'raw type' of [cls]. That is, the instantiation of [cls]
+  /// where all types arguments are `dynamic`.
+  InterfaceType getRawType(ClassEntity cls);
+
+  /// Returns the 'this type' of [cls]. That is, the instantiation of [cls]
+  /// where the type arguments are the type variables of [cls].
+  InterfaceType getThisType(ClassEntity cls);
+
+  /// Returns `true` if [a] is a subtype of [b].
+  bool isSubtype(DartType a, DartType b);
 }