prevent multiple promise resolution

This was handled for some code paths but not all.

lib/rsvp/promise.js

@@ -10,8 +10,7 @@ function isFunction(x){
 }
 
 var Promise = function(resolver) {
-  var promise = this,
-  resolved = false;
+  var promise = this;
 
   if (typeof resolver !== 'function') {
     throw new TypeError('You must pass a resolver function as the sole argument to the promise constructor');
@@ -22,14 +21,10 @@ var Promise = function(resolver) {
   }
 
   var resolvePromise = function(value) {
-    if (resolved) { return; }
-    resolved = true;
     resolve(promise, value);
   };
 
   var rejectPromise = function(value) {
-    if (resolved) { return; }
-    resolved = true;
     reject(promise, value);
   };
 
@@ -88,7 +83,9 @@ var invokeCallback = function(type, promise, callback, event) {
 
 Promise.prototype = {
   constructor: Promise,
-
+  isFulfilled: undefined,
+  isRejected: undefined,
+  isResolved: undefined,
   then: function(done, fail) {
     this.off('error', onerror);
 
@@ -158,6 +155,9 @@ function handleThenable(promise, value) {
 }
 
 function fulfill(promise, value) {
+  if (promise.isResolved){ return; }
+  promise.isResolved = true;
+
   config.async(function() {
     promise.trigger('promise:resolved', { detail: value });
     promise.isFulfilled = true;
@@ -166,6 +166,9 @@ function fulfill(promise, value) {
 }
 
 function reject(promise, value) {
+  if (promise.isResolved){ return; }
+  promise.isResolved = true;
+
   config.async(function() {
     promise.trigger('promise:failed', { detail: value });
     promise.isRejected = true;