Promise assimilation fix.

src/promise.js

Index: src/promise.js
diff --git a/src/promise.js b/src/promise.js
index 443a3b8c01a15d2d8cd4de98e4dfb10219fcb511..1724aa3f9fb51d06aa2a673f93ad48c663c9f7a5 100644
--- a/src/promise.js
+++ b/src/promise.js
@@ -106,7 +106,7 @@ var lastMicrotaskId = 0;
       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);
@@ -151,6 +151,17 @@ var lastMicrotaskId = 0;
     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)
   }