Implement AP2 Promises

LayoutTests/fast/js/resources/Promise-simple-in-workers.js

 importScripts('./js-test-pre.js');
 
 description('Test Promise.');
 
 var global = this;
 
 global.jsTestIsAsync = true;
 
 var resolve;
 
 var firstPromise = new Promise(function(newResolve) {
   global.thisInInit = this;
   resolve = newResolve;
 });
 
 var secondPromise = firstPromise.then(function(result) {
   global.thisInFulfillCallback = this;
-  shouldBeTrue('thisInFulfillCallback === secondPromise');
+  shouldBeFalse('thisInFulfillCallback === secondPromise');
+  shouldBeTrue('thisInFulfillCallback === global');
   global.result = result;
   shouldBeEqualToString('result', 'hello');
   finishJSTest();
 });
 
-shouldBeTrue('thisInInit === firstPromise');
+shouldBeFalse('thisInInit === firstPromise');
+shouldBeTrue('thisInInit === global');
 
 resolve('hello');