Promise constructor should not be enumerable.

src/promise.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 290 matching lines @@
     deferred.reject(e)
   }
   return deferred.promise;
 }
 
 //-------------------------------------------------------------------
 
 function SetUpPromise() {
   %CheckIsBootstrapping()
   var global_receiver = %GlobalReceiver(global);
-  global_receiver.Promise = $Promise;
+  $Object.defineProperty(global_receiver, 'Promise', {

[rossberg, 2014/03/26 09:59:37]

You can use %SetProperty directly, like I did in the rolled-back CL:

https://codereview.chromium.org/206163004/diff/1/src/promise.js#newcode308

Just replace NONE with DONT_ENUM.

[yhirano, 2014/03/26 10:09:12]

Thanks, done.

+    value: $Promise,
+    writable: true,
+    configurable: true
+  });
   InstallFunctions($Promise, DONT_ENUM, [
     "defer", PromiseDeferred,
     "accept", PromiseResolved,
     "reject", PromiseRejected,
     "all", PromiseAll,
     "race", PromiseOne,
     "resolve", PromiseCast
   ]);
   InstallFunctions($Promise.prototype, DONT_ENUM, [
     "chain", PromiseChain,
     "then", PromiseThen,
     "catch", PromiseCatch
   ]);
 }
 
 SetUpPromise();