Fix Promise.resolve/Promise.reject unnecessarily scheduling a microtask.

src/promise.js

Index: src/promise.js
diff --git a/src/promise.js b/src/promise.js
index 7d5be882f4c1ad161f2816ad70badeef614bcb40..d38cdaa482487e84aaf65f1b021bb457bf48a319 100644
--- a/src/promise.js
+++ b/src/promise.js
@@ -74,7 +74,8 @@ var lastMicrotaskId = 0;
 
   function PromiseDone(promise, status, value, promiseQueue) {
     if (GET_PRIVATE(promise, promiseStatus) === 0) {
-      PromiseEnqueue(value, GET_PRIVATE(promise, promiseQueue), status);
+      var tasks = GET_PRIVATE(promise, promiseQueue);
+      if (tasks.length) PromiseEnqueue(value, tasks, status);
       PromiseSet(promise, status, value);
     }
   }