Implement least upper bound.

sdk/lib/_internal/compiler/implementation/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 '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 10 matching lines @@
                                  Selector,
                                  Constant,
                                  Compiler;
 
 import '../dart_types.dart';
 
 import '../scanner/scannerlib.dart' show Token,
                                          isUserDefinableOperator,
                                          isMinusOperator;
 
+import '../ordered_typeset.dart' show OrderedTypeSet;
+
 const int STATE_NOT_STARTED = 0;
 const int STATE_STARTED = 1;
 const int STATE_DONE = 2;
 
 class ElementCategory {
   /**
    * Represents things that we don't expect to find when looking in a
    * scope.
    */
   static const int NONE = 0;
@@ skipping 788 matching lines @@
    * available until the type of the element has been computed through
    * [computeType].
    */
   Link<DartType> get typeVariables;
 }
 
 abstract class ClassElement extends TypeDeclarationElement
     implements ScopeContainerElement {
   int get id;
 
+  /// The length of the longest inheritance path from [:Object:].
+  int get hierarchyDepth;
+
   InterfaceType get rawType;
   InterfaceType get thisType;
 
   ClassElement get superclass;
 
   DartType get supertype;
+  OrderedTypeSet get allSupertypesAndSelf;
   Link<DartType> get allSupertypes;
   Link<DartType> get interfaces;
 
   bool get hasConstructor;
   Link<Element> get constructors;
 
   ClassElement get patch;
   ClassElement get origin;
   ClassElement get declaration;
   ClassElement get implementation;
 
   int get supertypeLoadState;
   int get resolutionState;
   bool get isResolved;
   String get nativeTagInfo;
 
   bool get isMixinApplication;
   bool get isUnnamedMixinApplication;
   bool get hasBackendMembers;
   bool get hasLocalScopeMembers;
 
   // TODO(kasperl): These are bit fishy. Do we really need them?
   void set thisType(InterfaceType value);
   void set supertype(DartType value);
-  void set allSupertypes(Link<DartType> value);
   void set interfaces(Link<DartType> value);
   void set patch(ClassElement value);
   void set origin(ClassElement value);
   void set supertypeLoadState(int value);
   void set resolutionState(int value);
   void set nativeTagInfo(String value);
 
   bool isObject(Compiler compiler);
   bool isSubclassOf(ClassElement cls);
   bool implementsInterface(ClassElement intrface);
@@ skipping 98 matching lines @@
   int get resolutionState;
   Token get beginToken;
   Token get endToken;
 
   // TODO(kasperl): Try to get rid of these.
   void set annotatedElement(Element value);
   void set resolutionState(int value);
 
   MetadataAnnotation ensureResolved(Compiler compiler);
 }