Make sure builtin functions don't rely on __proto__.

src/proxy.js

 // Copyright 2011 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 59 matching lines @@
 
 
 ////////////////////////////////////////////////////////////////////////////////
 // Builtins
 ////////////////////////////////////////////////////////////////////////////////
 
 function DerivedConstructTrap(callTrap) {
   return function() {
     var proto = this.prototype
     if (!IS_SPEC_OBJECT(proto)) proto = $Object.prototype
-    var obj = new $Object()
-    obj.__proto__ = proto
+    var obj = { __proto__: proto };
     var result = %Apply(callTrap, obj, arguments, 0, %_ArgumentsLength());
     return IS_SPEC_OBJECT(result) ? result : obj
   }
 }
 
 function DelegateCallAndConstruct(callTrap, constructTrap) {
   return function() {
     return %Apply(%_IsConstructCall() ? constructTrap : callTrap,
                   this, arguments, 0, %_ArgumentsLength())
   }
@@ skipping 93 matching lines @@
 }
 
 function ProxyEnumerate(proxy) {
   var handler = %GetHandler(proxy)
   if (IS_UNDEFINED(handler.enumerate)) {
     return %Apply(DerivedEnumerateTrap, handler, [], 0, 0)
   } else {
     return ToStringArray(handler.enumerate(), "enumerate")
   }
 }