WebUI fixes for SDK 0.8.10

lib/observe/list.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.
 
 library web_ui.observe.list;
 
+import 'dart:collection';
+
 import 'observable.dart';
-import 'package:web_ui/src/utils_observe.dart' show Arrays, ListMixinWorkaround;
+import 'package:web_ui/src/utils_observe.dart' show Arrays;
 
 /**
  * Represents an observable list of model values. If any items are added,
  * removed, or replaced, then observers that are registered with
  * [observe] will be notified.
  */
-class ObservableList<E> extends ListMixinWorkaround with Observable
-    implements List<E> {
+class ObservableList<E> extends ListBase<E> with Observable {
 
   /** The inner [List<E>] with the actual storage. */
   final List<E> _list;
 
   /**
    * Creates an observable list of the given [length].
    *
    * If no [length] argument is supplied an extendable list of
    * length 0 is created.
    *
@@ skipping 129 matching lines @@
 
   String toString() {
     if (observeReads) {
       for (int i = 0; i < length; i++) {
         notifyRead(this, ChangeRecord.INDEX, i);
       }
     }
     return _list.toString();
   }
 }