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

sky/sdk/lib/framework/components2/radio.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 'package:sky/framework/theme2/colors.dart' as colors;
 
 import '../fn2.dart';
 import '../rendering/object.dart';
 import 'button_base.dart';
 import 'ink_well.dart';
 import 'dart:sky' as sky;
 
 typedef void ValueChanged(value);
 
 class Radio extends ButtonBase {
 
   Radio({
     Object key,
-    this.onChanged,
     this.value,
-    this.groupValue
+    this.groupValue,
+    this.onChanged
   }) : super(key: key);
 
   Object value;
   Object groupValue;
   ValueChanged onChanged;
 
+  void syncFields(Radio source) {
+    value = source.value;
+    groupValue = source.groupValue;
+    onChanged = source.onChanged;
+    super.syncFields(source);
+  }
+
   UINode buildContent() {
     // TODO(jackson): This should change colors with the theme
     Color color = highlight ? colors.Purple[500] : const Color(0x8A000000);
     const double diameter = 16.0;
     const double outerRadius = diameter / 2;
     const double innerRadius = 5.0;
     return new EventListenerNode(
       new Container(
         margin: const EdgeDims.symmetric(horizontal: 5.0),
         width: diameter,
@@ skipping 18 matching lines @@
       ),
       onGestureTap: _handleClick
     );
   }
 
   void _handleClick(_) {
     onChanged(value);
   }
 
 }