Re-apply "Implement operator== and hashCode for bound closures."

sdk/lib/_internal/compiler/implementation/compiler.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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 288 matching lines @@
   LibraryElement coreLibrary;
   LibraryElement isolateLibrary;
   LibraryElement isolateHelperLibrary;
   LibraryElement jsHelperLibrary;
   LibraryElement interceptorsLibrary;
   LibraryElement foreignLibrary;
   LibraryElement mainApp;
 
   ClassElement objectClass;
   ClassElement closureClass;
+  ClassElement boundClosureClass;
   ClassElement dynamicClass;
   ClassElement boolClass;
   ClassElement numClass;
   ClassElement intClass;
   ClassElement doubleClass;
   ClassElement stringClass;
   ClassElement functionClass;
   ClassElement nullClass;
   ClassElement listClass;
   ClassElement typeClass;
@@ skipping 380 matching lines @@
 
     final List missingHelperClasses = [];
     ClassElement lookupHelperClass(String name) {
       ClassElement result = jsHelperLibrary.find(new SourceString(name));
       if (result == null) {
         missingHelperClasses.add(name);
       }
       return result;
     }
     jsInvocationMirrorClass = lookupHelperClass('JSInvocationMirror');
+    boundClosureClass = lookupHelperClass('BoundClosure');
     closureClass = lookupHelperClass('Closure');
     dynamicClass = lookupHelperClass('Dynamic_');
     nullClass = lookupHelperClass('Null');
     if (!missingHelperClasses.isEmpty) {
       internalErrorOnElement(jsHelperLibrary,
           'dart:_js_helper library does not contain required classes: '
           '$missingHelperClasses');
     }
 
     types = new Types(this, dynamicClass);
@@ skipping 617 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }