Converting tests over to using event streams.

tools/dom/src/_Testing.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.
-
-part of html;
-
-// TODO(rnystrom): add a way to supress public classes from DartDoc output.
-// TODO(jacobr): we can remove this class now that we are using the $dom_
-// convention for deprecated methods rather than truly private methods.
-/**
- * This class is intended for testing purposes only.
- */
-class Testing {
-  static void addEventListener(EventTarget target, String type, EventListener listener, bool useCapture) {
-    target.$dom_addEventListener(type, listener, useCapture);
-  }
-  static void removeEventListener(EventTarget target, String type, EventListener listener, bool useCapture) {
-    target.$dom_removeEventListener(type, listener, useCapture);
-  }
-
-}