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

sky/sdk/lib/framework/components2/drawer_header.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 '../fn2.dart';
 import '../theme2/colors.dart';
 import '../theme2/view_configuration.dart';
 
 class DrawerHeader extends Component {
 
   DrawerHeader({ Object key, this.children }) : super(key: key);
 
-  List<UINode> children;
+  final List<UINode> children;
 
   UINode build() {
     return new Container(
       key: 'drawer-header-outside',
       height: kStatusBarHeight + kMaterialDrawerHeight,
       decoration: new BoxDecoration(
         backgroundColor: BlueGrey[50],
         border: const Border(
           bottom: const BorderSide(
             color: const Color(0xFFD1D9E1),
@@ skipping 15 matching lines @@
               direction: FlexDirection.horizontal,
               children: children
             )
           )
         ]
       )
     );
   }
 
 }