Improve equivalence testing of unnamed mixin applications.

pkg/compiler/lib/src/elements/elements.dart

 // Copyright (c) 2012, 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.
 
 library elements;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
 import '../constants/constructors.dart';
@@ skipping 1508 matching lines @@
   void forEachInterfaceMember(f(MemberSignature member));
 
   /// Returns the type of the 'call' method in the interface of this class, or
   /// `null` if the interface has no 'call' method.
   FunctionType get callType;
 }
 
 abstract class MixinApplicationElement extends ClassElement {
   ClassElement get mixin;
   InterfaceType get mixinType;
+
+  /// If this is an unnamed mixin application [subclass] is the subclass for
+  /// which this mixin application is created.
+  ClassElement get subclass;
 }
 
 /// Enum declaration.
 abstract class EnumClassElement extends ClassElement {
   /// The static fields implied by the enum values.
   List<EnumConstantElement> get enumValues;
 }
 
 /// An enum constant value.
 abstract class EnumConstantElement extends FieldElement {
@@ skipping 291 matching lines @@
   /// by a field.
   bool get isDeclaredByField;
 
   /// Returns `true` if this member is abstract.
   bool get isAbstract;
 
   /// If abstract, [implementation] points to the overridden concrete member,
   /// if any. Otherwise [implementation] points to the member itself.
   Member get implementation;
 }