Promise assimilation fix.

src/promise.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.
 
 "use strict";
 
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $Object = global.Object
 // var $WeakMap = global.WeakMap
@@ skipping 88 matching lines @@
     }
     return x;
   }
 
   function PromiseHandle(value, handler, deferred) {
     try {
       %DebugPushPromise(deferred.promise);
       var result = handler(value);
       if (result === deferred.promise)
         throw MakeTypeError('promise_cyclic', [result]);
-      else if (IsPromise(result))
+      else if (IsUnforgedPromise(result))
         %_CallFunction(result, deferred.resolve, deferred.reject, PromiseChain);
       else
         deferred.resolve(result);
     } catch (exception) {
       try { deferred.reject(exception); } catch (e) { }
     } finally {
       %DebugPopPromise();
     }
   }
 
@@ skipping 24 matching lines @@
 
   // -------------------------------------------------------------------
   // Define exported functions.
 
   // For bootstrapper.
 
   IsPromise = function IsPromise(x) {
     return IS_SPEC_OBJECT(x) && HAS_DEFINED_PRIVATE(x, promiseStatus);
   }
 
+  IsUnforgedPromise = function IsUnforgedPromise(x) {

[arv (Not doing code reviews), 2015/04/17 14:32:06]

Does this need to be exported?

[yhirano, 2015/04/30 05:05:16]

Deleted.

+    if (!IsPromise(x)) {
+      return false;
+    }
+    try {
+      return x.then === PromiseThen;

[arv (Not doing code reviews), 2015/04/17 14:32:06]

This needs a test to ensure that the getter is invoked at the right time and the
correct amount of times.

[arv (Not doing code reviews), 2015/04/17 14:32:06]

Which section of the ES6 spec defines this? I cannot find anything about this?

[yhirano, 2015/04/30 05:05:16]

Deleted.

[yhirano, 2015/04/30 05:05:16]

Deleted.

+    } catch (e) {
+      return false;
+    }
+  }
+
   PromiseCreate = function PromiseCreate() {
     return new $Promise(PromiseNopResolver)
   }
 
   PromiseResolve = function PromiseResolve(promise, x) {
     PromiseDone(promise, +1, x, promiseOnResolve)
   }
 
   PromiseReject = function PromiseReject(promise, r) {
     // Check promise status to confirm that this reject has an effect.
@@ skipping 211 matching lines @@
     "race", PromiseOne,
     "resolve", PromiseCast
   ]);
   InstallFunctions($Promise.prototype, DONT_ENUM, [
     "chain", PromiseChain,
     "then", PromiseThen,
     "catch", PromiseCatch
   ]);
 
 })();