Add Timer implementation for dart2js. Also moves tests to appropriate location.

lib/isolate/dart2js/compiler_hooks.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // This file contains functions that are used in the code generated by
 // the dart2js compiler.
 
 /**
  * Wrapper that takes the dart entry point and runs it within an isolate. The
  * dart2js compiler will inject a call of the form
  * [: startRootIsolate(main); :] when it determines that this wrapping
  * is needed. For single-isolate applications (e.g. hello world), this
  * call is not emitted.
  */
 void startRootIsolate(entry) {
   _globalState = new _Manager();
 
   // Don't start the main loop again, if we are in a worker.
   if (_globalState.isWorker) return;
   final rootContext = new _IsolateContext();
   _globalState.rootContext = rootContext;
   _fillStatics(rootContext);
 
   // BUG(5151491): Setting currentContext should not be necessary, but
   // because closures passed to the DOM as event handlers do not bind their
   // isolate automatically we try to give them a reasonable context to live in
   // by having a "default" isolate (the first one created).
   _globalState.currentContext = rootContext;
 
+  if (_window != null)  {
+    rootContext.eval(() => _setTimerFactoryClosure( _timerFactory));
+  }
   rootContext.eval(entry);
   _globalState.topEventLoop.run();
 }