Implement AP2 Promises

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

 importScripts('./js-test-pre.js');
 
 var global = this;
 global.jsTestIsAsync = true;
 
 description('Test Promise.');
 
 var thisInInit;
 var resolve, reject;
 var promise = new Promise(function(newResolve, newReject) {
   thisInInit = this;
   resolve = newResolve;
   reject = newReject;
 });
 
 shouldBeTrue('promise instanceof Promise');
 shouldBe('promise.constructor', 'Promise');
-shouldBe('thisInInit', 'promise');
+shouldBeFalse('thisInInit === promise');
+shouldBeTrue('thisInInit === global');
 shouldBeTrue('resolve instanceof Function');
 shouldBeTrue('reject instanceof Function');
 
 shouldThrow('new Promise()', '"TypeError: Promise constructor takes a function argument"');
 shouldThrow('new Promise(37)', '"TypeError: Promise constructor takes a function argument"');
 
 shouldNotThrow('promise = new Promise(function() { throw Error("foo"); })');
 promise.then(undefined, function(result) {
   global.result = result;
   shouldBeEqualToString('result.message', 'foo');
 });
 
 new Promise(function(resolve) {
   resolve("hello");
   throw Error("foo");
 }).then(function(result) {
   global.result = result;
   testPassed('fulfilled');
   shouldBeEqualToString('result', 'hello');
   finishJSTest();
 }, function(result) {
   global.result = result;
   testFailed('rejected');
   finishJSTest();
 });