Make Icon work using space-aged base-url technology.

sky/sdk/lib/framework/components2/menu_item.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 'button_base.dart';
 import 'icon.dart';
 import 'ink_well.dart';
 
 class MenuItem extends ButtonBase {
@@ skipping 26 matching lines @@
 
   MenuItem({ Object key, this.icon, this.children, this.onGestureTap }) : super(key: key);
 
   UINode buildContent() {
     return new EventListenerNode(
       new StyleNode(
         new InkWell(
           children: [
             new StyleNode(
               new Icon(
-                size: 24.0,
+                size: 24,
                 type: "${icon}_grey600"
               ),
               _iconStyle
             ),
             new ParentDataNode(
               new FlexContainer(
                 direction: FlexDirection.Row,
                 style: _labelStyle,
                 children: children
               ),
               _labelFlex
             )
           ]
         ),
         highlight ? _highlightStyle : _style
       ),
       onGestureTap: onGestureTap
     );
   }
 }