Switch scroll physics over to using newton

sky/sdk/example/widgets/card_collection.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:sky' as sky;
 
 import 'package:vector_math/vector_math.dart';
 import 'package:sky/animation/animation_performance.dart';
 import 'package:sky/animation/scroll_behavior.dart';
 import 'package:sky/base/lerp.dart';
@@ skipping 29 matching lines @@
     builder = source.builder;
     token = source.token;
     super.syncFields(source);
   }
 
   ScrollBehavior createScrollBehavior() => new OverscrollBehavior();
   OverscrollBehavior get scrollBehavior => super.scrollBehavior;
 
   void _handleSizeChanged(Size newSize) {
     setState(() {
-      scrollBehavior.containerHeight = newSize.height;
-      scrollBehavior.contentsHeight = 5000.0;
+      scrollBehavior.containerSize = newSize.height;
+      scrollBehavior.contentsSize = 5000.0;
     });
   }
 
   Widget buildContent() {
     return new SizeObserver(
       callback: _handleSizeChanged,
       child: new BlockViewport(
         builder: builder,
         startOffset: scrollOffset,
         token: token
       )
     );
   }
 }
 
 class CardCollectionApp extends App {
 
   final TextStyle cardLabelStyle =
     new TextStyle(color: White, fontSize: 18.0, fontWeight: bold);
 
   final List<double> cardHeights = [
-    48.0, 64.0, 82.0, 46.0, 60.0, 55.0, 84.0, 96.0, 50.0, 
+    48.0, 64.0, 82.0, 46.0, 60.0, 55.0, 84.0, 96.0, 50.0,
     48.0, 64.0, 82.0, 46.0, 60.0, 55.0, 84.0, 96.0, 50.0,
     48.0, 64.0, 82.0, 46.0, 60.0, 55.0, 84.0, 96.0, 50.0
   ];
 
   List<int> visibleCardIndices;
-  
+
   CardCollectionApp() {
     _activeCardTransform = new AnimatedContainer()
       ..position = new AnimatedType<Point>(Point.origin)
       ..opacity = new AnimatedType<double>(1.0, end: 0.0);
 
     _activeCardAnimation = _activeCardTransform.createPerformance(
         [_activeCardTransform.position, _activeCardTransform.opacity],
         duration: new Duration(milliseconds: _kCardDismissFadeoutMS));
     _activeCardAnimation.addListener(_handleAnimationProgressChanged);
 
@@ skipping 131 matching lines @@
     return new Scaffold(
       toolbar: new ToolBar(center: new Text('Swipe Away')),
       body: new SizeObserver(child: cardCollection, callback: _handleSizeChanged)
     );
   }
 }
 
 void main() {
   runApp(new CardCollectionApp());
 }