implement dirty checking for @observable objects

pkg/mdv/test/observe_utils.dart

Index: pkg/mdv/test/observe_utils.dart
diff --git a/pkg/mdv/test/observe_utils.dart b/pkg/mdv/test/observe_utils.dart
deleted file mode 100644
index d3f33e1b121f946948c7cff7970c29e0529d5244..0000000000000000000000000000000000000000
--- a/pkg/mdv/test/observe_utils.dart
+++ /dev/null
@@ -1,16 +0,0 @@
-// 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 observe_utils;
-
-import 'package:observe/observe.dart';
-
-toSymbolMap(Map map) {
-  var result = new ObservableMap.linked();
-  map.forEach((key, value) {
-    if (value is Map) value = toSymbolMap(value);
-    result[new Symbol(key)] = value;
-  });
-  return result;
-}