Don't auto-send credentials on XHR.get

lib/dom/src/_XMLHttpRequestUtils.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.
 
 class _XMLHttpRequestUtils {
 
   // Helper for factory XMLHttpRequest.get
   static XMLHttpRequest get(String url,
-                            onSuccess(XMLHttpRequest request)) {
+                            onSuccess(XMLHttpRequest request),
+                            bool withCredentials) {
     final request = new XMLHttpRequest();
     request.open('GET', url, true);
 
-    // TODO(terry): Validate after client login added if necessary to forward
-    //              cookies to server.
-    request.withCredentials = true;
+    request.withCredentials = withCredentials;
 
     // Status 0 is for local XHR request.
     request.on.readyStateChange.add((e) {
       if (request.readyState == XMLHttpRequest.DONE &&
           (request.status == 200 || request.status == 0)) {
         onSuccess(request);
       }
     });
 
     request.send();
 
     return request;
   }
 }