Remove unused 'receiver' field from generators

src/debug/mirrors.js

 // Copyright 2006-2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils) {
 "use strict";
 
 // ----------------------------------------------------------------------------
 // Imports
 
@@ skipping 1425 matching lines @@
 
 
 GeneratorMirror.prototype.func = function() {
   if (!this.func_) {
     this.func_ = MakeMirror(%GeneratorGetFunction(this.value_));
   }
   return this.func_;
 };
 
 
-GeneratorMirror.prototype.receiver = function() {
-  if (!this.receiver_) {
-    this.receiver_ = MakeMirror(%GeneratorGetReceiver(this.value_));
-  }
-  return this.receiver_;
-};
-
-
 /**
  * Base mirror object for properties.
  * @param {ObjectMirror} mirror The mirror object having this property
  * @param {string} name The name of the property
  * @param {Array} details Details about the property
  * @constructor
  * @extends Mirror
  */
 function PropertyMirror(mirror, name, details) {
   %_Call(Mirror, this, MirrorType.PROPERTY_TYPE);
@@ skipping 1308 matching lines @@
     }
   }
 
   if (mirror.isGenerator()) {
     // Add generator specific properties.
 
     // Either 'running', 'closed', or 'suspended'.
     content.status = mirror.status();
 
     content.func = this.serializeReference(mirror.func())
-    content.receiver = this.serializeReference(mirror.receiver())
 
     // If the generator is suspended, the content add line/column properties.
     serializeLocationFields(mirror.sourceLocation(), content);
 
     // TODO(wingo): Also serialize a reference to the context (scope chain).
   }
 
   if (mirror.isDate()) {
     // Add date specific properties.
     content.value = mirror.value();
@@ skipping 245 matching lines @@
 // Functions needed by the debugger runtime.
 utils.InstallFunctions(utils, DONT_ENUM, [
   "ClearMirrorCache", ClearMirrorCache
 ]);
 
 // Export to debug.js
 utils.Export(function(to) {
   to.MirrorType = MirrorType;
 });
 })