Make __proto__ a foreign callback on Object.prototype.

src/factory.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 258 matching lines @@
   // JS objects are pretenured when allocated by the bootstrapper and
   // runtime.
   Handle<JSObject> NewJSObject(Handle<JSFunction> constructor,
                                PretenureFlag pretenure = NOT_TENURED);
 
   // Global objects are pretenured.
   Handle<GlobalObject> NewGlobalObject(Handle<JSFunction> constructor);
 
   // JS objects are pretenured when allocated by the bootstrapper and
   // runtime.
-  Handle<JSObject> NewJSObjectFromMap(Handle<Map> map);
+  Handle<JSObject> NewJSObjectFromMap(Handle<Map> map,
+                                      PretenureFlag pretenure = NOT_TENURED);
 
   // JS modules are pretenured.
   Handle<JSModule> NewJSModule(Handle<Context> context,
                                Handle<ScopeInfo> scope_info);
 
   // JS arrays are pretenured when allocated by the parser.
   Handle<JSArray> NewJSArray(
       int capacity,
       ElementsKind elements_kind = TERMINAL_FAST_ELEMENTS_KIND,
       PretenureFlag pretenure = NOT_TENURED);
@@ skipping 228 matching lines @@
   // Update the map cache in the native context with (keys, map)
   Handle<MapCache> AddToMapCache(Handle<Context> context,
                                  Handle<FixedArray> keys,
                                  Handle<Map> map);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_