Rename BlockContainer, StackContainer, and FlexContainer

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';
 
 const BoxDecoration _kHighlightDecoration = const BoxDecoration(
@@ skipping 28 matching lines @@
     return new EventListenerNode(
       new Container(
         child: new InkWell(
           children: [
             new Padding(
               child: new Icon(type: "${icon}_grey600", size: 24),
               padding: const EdgeDims.symmetric(horizontal: 16.0)
             ),
             new FlexExpandingChild(
               new Padding(
-                child: new FlexContainer(
-                  direction: FlexDirection.horizontal,
-                  children: children
-                ),
+                child: new Flex(children, direction: FlexDirection.horizontal),
                 padding: const EdgeDims.symmetric(horizontal: 16.0)
               ),
               flex: 1
             )
           ]
         ),
         height: 48.0,
         decoration: highlight ? _kHighlightDecoration : _kHighlightBoring
       ),
       onGestureTap: onGestureTap
     );
   }
 }