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

sky/sdk/lib/framework/components2/animated_component.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 'dart:async';
 
 typedef void SetterFunction(double value);
 
 abstract class AnimatedComponent extends Component {
 
   AnimatedComponent({ Object key }) : super(key: key, stateful: true);
 
+  void syncFields(AnimatedComponent source) { }
+
   animate(AnimatedValue value, SetterFunction setter) {
     setter(value.value);
     StreamSubscription<double> subscription;
     onDidMount(() {
       subscription = value.onValueChanged.listen((_) {
         setter(value.value);
         scheduleBuild();
       });
     });
     onDidUnmount(() {
       if (subscription != null) {
         subscription.cancel();
         subscription = null;
       }
     });
   }
 
 }