Change how we narrow the "root" type on RenderObjectWrappers.

sky/sdk/lib/framework/components2/ink_well.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 '../animation/animated_value.dart';
 import '../animation/curves.dart';
 import '../fn2.dart';
 import '../rendering/box.dart';
 import '../rendering/flex.dart';
 import '../rendering/object.dart';
@@ skipping 87 matching lines @@
       canvas.restore();
     }
     super.paint(canvas);
   }
 }
 
 class InkWellWrapper extends OneChildRenderObjectWrapper {
   InkWellWrapper({ UINode child, Object key })
     : super(child: child, key: key);
 
-  RenderInkWell root;
+  RenderInkWell get root => super.root as RenderInkWell;
 
   RenderInkWell createNode() => new RenderInkWell();
 }
 
 class InkWell extends Component {
   InkWell({ Object key, this.children }) : super(key: key);
 
   final List<UINode> children;
 
   UINode build() {
     return new InkWellWrapper(
       child: new FlexContainer(
         direction: FlexDirection.horizontal,
         justifyContent: FlexJustifyContent.center,
         children: children
       )
     );
   }
 }