Remove one more use of mirrors: Components now have to explicitly sync their fields.

sky/sdk/lib/framework/components2/popup_menu.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import '../animation/animated_value.dart';
 import '../fn2.dart';
 import '../theme2/colors.dart';
 import '../theme2/shadows.dart';
 import 'animated_component.dart';
 import 'dart:async';
@@ skipping 42 matching lines @@
 class PopupMenu extends AnimatedComponent {
 
   PopupMenu({ Object key, this.controller, this.items, this.level })
       : super(key: key) {
     animate(controller.position, (double value) {
       _position = value;
     });
     // onDidMount(_measureSize);
   }
 
+  PopupMenuController controller;
   List<List<UINode>> items;
   int level;
-  PopupMenuController controller;
+
+  void syncFields(PopupMenu source) {
+    controller = source.controller;
+    items = source.items;
+    level = source.level;
+    super.syncFields(source);
+  }
 
   double _position;
   // int _width;
   // int _height;
 
   double _opacityFor(int i) {
     if (_position == null || _position == 1.0)
       return null;
     double unit = 1.0 / items.length;
     double duration = 1.5 * unit;
@@ skipping 33 matching lines @@
         decoration: new BoxDecoration(
           backgroundColor: Grey[50],
           borderRadius: 2.0,
           boxShadow: Shadow[level]),
         child: new BlockContainer(children: children)
       )
     );
   }
 
 }