Rationalize Dart mojo and sky package structure

sky/sdk/lib/framework/components/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 '../fn.dart';
 import '../layout.dart';
 import '../theme/colors.dart';
 import '../theme/view_configuration.dart';
 
 class DrawerHeader extends Component {
@@ skipping 26 matching lines @@
         ),
         new Container(
           key: 'Label',
           style: _labelStyle,
           children: children
         )
       ]
     );
   }
 }