[builtins] Properly optimize Object.prototype.isPrototypeOf.

src/js/v8natives.js

 // Copyright 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) {
 
 %CheckIsBootstrapping();
 
 // ----------------------------------------------------------------------------
 // Imports
 
 var GlobalObject = global.Object;
 var iteratorSymbol = utils.ImportNow("iterator_symbol");
 
 // ----------------------------------------------------------------------------
 // Object
 
 // ES6 19.1.3.5 Object.prototype.toLocaleString([reserved1 [,reserved2]])
 function ObjectToLocaleString() {
   CHECK_OBJECT_COERCIBLE(this, "Object.prototype.toLocaleString");
   return this.toString();
 }
 
-
-// ES6 19.1.3.3 Object.prototype.isPrototypeOf(V)
-function ObjectIsPrototypeOf(V) {
-  if (!IS_RECEIVER(V)) return false;
-  var O = TO_OBJECT(this);
-  return %HasInPrototypeChain(V, O);
-}
-
-
 // ES6 7.3.9
 function GetMethod(obj, p) {
   var func = obj[p];
   if (IS_NULL_OR_UNDEFINED(func)) return UNDEFINED;
   if (IS_CALLABLE(func)) return func;
   throw %make_type_error(kCalledNonCallable, typeof func);
 }
 
 // ES6 19.1.1.1
 function ObjectConstructor(x) {
@@ skipping 12 matching lines @@
 %SetCode(GlobalObject, ObjectConstructor);
 
 %AddNamedProperty(GlobalObject.prototype, "constructor", GlobalObject,
                   DONT_ENUM);
 
 // Set up non-enumerable functions on the Object.prototype object.
 utils.InstallFunctions(GlobalObject.prototype, DONT_ENUM, [
   // toString is added in bootstrapper.cc
   "toLocaleString", ObjectToLocaleString,
   // valueOf is added in bootstrapper.cc.
-  "isPrototypeOf", ObjectIsPrototypeOf,
+  // isPrototypeOf is added in bootstrapper.cc.
   // propertyIsEnumerable is added in bootstrapper.cc.
   // __defineGetter__ is added in bootstrapper.cc.
   // __lookupGetter__ is added in bootstrapper.cc.
   // __defineSetter__ is added in bootstrapper.cc.
   // __lookupSetter__ is added in bootstrapper.cc.
 ]);
 
 
 // ----------------------------------------------------------------------------
 // Iterator related spec functions.
@@ skipping 15 matching lines @@
 
 // ----------------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.GetIterator = GetIterator;
   to.GetMethod = GetMethod;
 });
 
 })