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

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

Index: sky/sdk/lib/framework/components2/animated_component.dart
diff --git a/sky/sdk/lib/framework/components2/animated_component.dart b/sky/sdk/lib/framework/components2/animated_component.dart
index d1dada90dbfeab2f8efe483c34c8bcdb11e334fe..4cc91e01d0c981dd4c8d4b6dfb36aaa922b6e995 100644
--- a/sky/sdk/lib/framework/components2/animated_component.dart
+++ b/sky/sdk/lib/framework/components2/animated_component.dart
@@ -12,6 +12,8 @@ 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;