Enqueue superclasses instead of supertypes.

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 '../compiler.dart' show
     Compiler;
 import '../constants/constructors.dart';
 import '../constants/expressions.dart';
@@ skipping 1374 matching lines @@
 
   ClassElement get patch;
   ClassElement get origin;
   ClassElement get declaration;
   ClassElement get implementation;
 
   String get nativeTagInfo;
 
   /// `true` if this class is an enum declaration.
   bool get isEnumClass;
+
+  /// `true` if this class is a mixin application, either named or unnamed.
   bool get isMixinApplication;
+
+  /// `true` if this class is a named mixin application, e.g.
+  ///
+  ///     class NamedMixinApplication = SuperClass with MixinClass;
+  ///
+  bool get isNamedMixinApplication;
+
+  /// `true` if this class is an unnamed mixin application, e.g. the synthesized
+  /// `SuperClass+MixinClass` mixin application class in:
+  ///
+  ///     class Class extends SuperClass with MixinClass {}
+  ///
   bool get isUnnamedMixinApplication;
+
   bool get hasBackendMembers;
   bool get hasLocalScopeMembers;
 
   /// Returns `true` if this class is `Object` from dart:core.
   bool get isObject;
 
   /// Returns `true` if this class implements [Function] either by directly
   /// implementing the interface or by providing a [call] method.
   bool implementsFunction(Compiler compiler);
 
@@ skipping 276 matching lines @@
   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;
 }