Converting tests over to using event streams.

tools/dom/src/_HttpRequestUtils.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;
 
 class _HttpRequestUtils {
 
   // Helper for factory HttpRequest.get
   static HttpRequest get(String url,
                             onComplete(HttpRequest request),
                             bool withCredentials) {
     final request = new HttpRequest();
     request.open('GET', url, true);
 
     request.withCredentials = withCredentials;
 
-    request.on.readyStateChange.add((e) {
+    request.onReadyStateChange.listen((e) {
       if (request.readyState == HttpRequest.DONE) {
         onComplete(request);
       }
     });
 
     request.send();
 
     return request;
   }
 }