Rationalize Dart mojo and sky package structure

sky/sdk/lib/framework/components/popup_menu.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 'animated_component.dart';
 import '../animation/animated_value.dart';
 import '../fn.dart';
 import '../theme/colors.dart';
 import 'dart:async';
 import 'dart:math' as math;
@@ skipping 95 matching lines @@
 
     return new Material(
       content: new Container(
         style: _style,
         inlineStyle: _inlineStyle(),
         children: children
       ),
       level: level);
   }
 }