[builtins] Also port the Object.prototype.__proto__ accessors to C++.

src/builtins/builtins.h

 // Copyright 2011 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.
 
 #ifndef V8_BUILTINS_BUILTINS_H_
 #define V8_BUILTINS_BUILTINS_H_
 
 #include "src/base/flags.h"
 #include "src/handles.h"
 
@@ skipping 521 matching lines @@
   CPP(ObjectIsExtensible)                                                     \
   CPP(ObjectIsFrozen)                                                         \
   CPP(ObjectIsSealed)                                                         \
   CPP(ObjectKeys)                                                             \
   CPP(ObjectLookupGetter)                                                     \
   CPP(ObjectLookupSetter)                                                     \
   CPP(ObjectPreventExtensions)                                                \
   /* ES6 section 19.1.3.6 Object.prototype.toString () */                     \
   TFJ(ObjectProtoToString, 1)                                                 \
   CPP(ObjectPrototypePropertyIsEnumerable)                                    \
+  CPP(ObjectPrototypeGetProto)                                                \
+  CPP(ObjectPrototypeSetProto)                                                \
   CPP(ObjectSeal)                                                             \
   CPP(ObjectValues)                                                           \
                                                                               \
   TFS(HasProperty, BUILTIN, kNoExtraICState, HasProperty)                     \
   TFS(InstanceOf, BUILTIN, kNoExtraICState, Compare)                          \
   TFS(ForInFilter, BUILTIN, kNoExtraICState, ForInFilter)                     \
                                                                               \
   /* Proxy */                                                                 \
   CPP(ProxyConstructor)                                                       \
   CPP(ProxyConstructor_ConstructStub)                                         \
@@ skipping 262 matching lines @@
 
   friend class Isolate;
 
   DISALLOW_COPY_AND_ASSIGN(Builtins);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_BUILTINS_BUILTINS_H_