[Effen] Convert action_bar.dart to using a FlexContainer.

sky/framework/fn.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.
 
 library fn;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:sky' as sky;
 import 'reflect.dart' as reflect;
@@ skipping 525 matching lines @@
     Style style,
     String inlineStyle
   }) : super(
     key: key,
     children: children,
     style: style,
     inlineStyle: inlineStyle
   );
 }
 
+class FlexContainer extends SkyElementWrapper {
+
+  RenderCSSFlex _root;
+  RenderCSSFlex _createNode() => new RenderCSSFlex(this, this.direction);
+
+  static final FlexContainer _emptyContainer = new FlexContainer();
+    // direction doesn't matter if it's empty
+
+  SkyNodeWrapper get _emptyNode => _emptyContainer;
+
+  final FlexDirection direction;
+
+  FlexContainer({
+    Object key,
+    List<UINode> children,
+    Style style,
+    String inlineStyle,
+    this.direction: FlexDirection.Row
+  }) : super(
+    key: key,
+    children: children,
+    style: style,
+    inlineStyle: inlineStyle
+  );
+
+  void _syncNode(UINode old) {
+    super._syncNode(old);
+    _root.direction = direction;
+  }
+}
+
 class Image extends SkyElementWrapper {
 
   RenderCSSImage _root;
   RenderCSSImage _createNode() => new RenderCSSImage(this, this.src, this.width, this.height);
 
   static final Image _emptyImage = new Image();
 
   SkyNodeWrapper get _emptyNode => _emptyImage;
 
   final String src;
@@ skipping 241 matching lines @@
   }
 
   void _buildIfDirty() {
     if (!_dirty || _defunct)
       return;
 
     _trace('$_key rebuilding...');
     _sync(null, _host, _root);
   }
 }