Make sure builtin functions don't rely on __proto__.

src/v8natives.js

 // 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 76 matching lines @@
     for (var i = 0; i < fields.length; i++) {
       %SetProperty(prototype, fields[i], void 0, DONT_ENUM | DONT_DELETE);
     }
   }
   for (var i = 0; i < methods.length; i += 2) {
     var key = methods[i];
     var f = methods[i + 1];
     %SetProperty(prototype, key, f, DONT_ENUM | DONT_DELETE | READ_ONLY);
     %SetNativeFlag(f);
   }
-  prototype.__proto__ = null;
+  %SetPrototype(prototype, null);
   %ToFastProperties(prototype);
 }
 
 
 // ----------------------------------------------------------------------------
 
 
 // ECMA 262 - 15.1.4
 function GlobalIsNaN(number) {
   if (!IS_NUMBER(number)) number = NonNumberToNumber(number);
@@ skipping 959 matching lines @@
 
   return propertyNames;
 }
 
 
 // ES5 section 15.2.3.5.
 function ObjectCreate(proto, properties) {
   if (!IS_SPEC_OBJECT(proto) && proto !== null) {
     throw MakeTypeError("proto_object_or_null", [proto]);
   }
-  var obj = new $Object();
-  obj.__proto__ = proto;
+  var obj = { __proto__: proto };
   if (!IS_UNDEFINED(properties)) ObjectDefineProperties(obj, properties);
   return obj;
 }
 
 
 // ES5 section 15.2.3.6.
 function ObjectDefineProperty(obj, p, attributes) {
   if (!IS_SPEC_OBJECT(obj)) {
     throw MakeTypeError("called_on_non_object", ["Object.defineProperty"]);
   }
@@ skipping 635 matching lines @@
 
 function SetUpFunction() {
   %CheckIsBootstrapping();
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetUpFunction();