Split layout2.dart into several files

sky/sdk/lib/framework/components2/scaffold.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 '../layout2.dart';
 import '../theme/typography.dart' as typography;
 import 'dart:sky' as sky;
 
 // RenderNode
 class RenderScaffold extends RenderDecoratedBox {
 
   RenderScaffold({
     BoxDecoration decoration,
     RenderBox toolbar,
     RenderBox body,
@@ skipping 197 matching lines @@
   void syncRenderNode(UINode old) {
     super.syncRenderNode(old);
     syncChild(toolbar, old is Scaffold ? old.toolbar : null, #toolbar);
     syncChild(body, old is Scaffold ? old.body : null, #body);
     syncChild(statusbar, old is Scaffold ? old.statusbar : null, #statusbar);
     syncChild(drawer, old is Scaffold ? old.drawer : null, #drawer);
     syncChild(floatingActionButton, old is Scaffold ? old.floatingActionButton : null, #floatingActionButton);
   }
 
 }