Fix the Sky tests

sky/sdk/lib/framework/rendering/box.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' as math;
 import 'dart:sky' as sky;
 import 'dart:typed_data';
 import 'object.dart';
 import '../painting/shadows.dart';
 import 'package:vector_math/vector_math.dart';
@@ skipping 938 matching lines @@
 
   ViewConstraints _rootConstraints;
   ViewConstraints get rootConstraints => _rootConstraints;
   void set rootConstraints(ViewConstraints value) {
     if (_rootConstraints == value)
       return;
     _rootConstraints = value;
     markNeedsLayout();
   }
 
-  ViewConstraints get constraints => super.constraints as ViewConstraints;
-
   void performLayout() {
     if (_rootConstraints.orientation != _orientation) {
       if (_orientation != null && child != null)
         child.rotate(oldAngle: _orientation, newAngle: _rootConstraints.orientation, time: timeForRotation);
       _orientation = _rootConstraints.orientation;
     }
     _size = new Size(_rootConstraints.width, _rootConstraints.height);
     assert(_size.height < double.INFINITY);
     assert(_size.width < double.INFINITY);
 
@@ skipping 53 matching lines @@
 
   void defaultPaint(RenderObjectDisplayList canvas) {
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is ParentDataType);
       canvas.paintChild(child, child.parentData.position);
       child = child.parentData.nextSibling;
     }
   }
 }