Fix Future.immediateError users.

tools/dom/src/ModelTreeObserver.dart

 // Copyright (c) 2013, 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 _ModelTreeObserver {
   static bool _initialized = false;
 
   /**
@@ skipping 68 matching lines @@
     // Catch and report them a global exceptions.
     try {
       if (node._hasLocalModel != true && node._model != model &&
           node._modelChangedStreams != null &&
           !node._modelChangedStreams.isEmpty) {
         node._model = model;
         node._modelChangedStreams.toList()
           .forEach((controller) => controller.add(node));
       }
     } catch (e, s) {
-      new Future.immediateError(e, s);
+      new Future.error(e, s);
     }
     for (var child = node.$dom_firstChild; child != null;
         child = child.nextNode) {
       if (child._hasLocalModel != true) {
         propagateModel(child, model, fullTree);
       } else if (fullTree) {
         propagateModel(child, child._model, true);
       }
     }
   }
 }