Address Ian's comments on layout2.dart

sky/examples/raw/simple_render_tree.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 'dart:math';
 import 'dart:sky';
 import 'package:sky/framework/layout2.dart';
 
 class RenderSolidColor extends RenderDecoratedBox {
   final int backgroundColor;
 
   RenderSolidColor(int backgroundColor)
       : super(new BoxDecoration(backgroundColor: backgroundColor)),
         backgroundColor = backgroundColor;
 
   BoxDimensions getIntrinsicDimensions(BoxConstraints constraints) {
     return new BoxDimensions.withConstraints(constraints, height: 200.0);
   }
 
   void layout(BoxConstraints constraints, { RenderNode relayoutSubtreeRoot }) {
-    setWidth(constraints, constraints.maxWidth);
-    setHeight(constraints, 200.0);
+    width = constraints.constrainWidth(constraints.maxWidth);
+    height = constraints.constrainHeight(200.0);
     layoutDone();
   }
 
   bool handlePointer(PointerEvent event, { double x: 0.0, double y: 0.0 }) {
     if (event.type == 'pointerdown') {
       setBoxDecoration(new BoxDecoration(backgroundColor: 0xFFFF0000));
       return true;
     }
 
     if (event.type == 'pointerup') {
@@ skipping 27 matching lines @@
       decoration: new BoxDecoration(backgroundColor: 0xFF00FFFF));
 
   root.add(new RenderSolidColor(0xFF00FF00));
   root.add(new RenderSolidColor(0xFF0000FF));
 
   renderView = new RenderView(root: root);
   renderView.layout(newWidth: view.width, newHeight: view.height);
 
   view.scheduleFrame();
 }