add initState, rename animated_container

sky/sdk/lib/widgets/scrollable.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:newton/newton.dart';
 
 import '../animation/animated_simulation.dart';
 import '../animation/scroll_behavior.dart';
@@ skipping 117 matching lines @@
   void settleScrollOffset() {
     _startSimulation();
   }
 
   void _stopSimulation() {
     _animation.stop();
   }
 
   void _startSimulation({ double velocity: 0.0 }) {
     _stopSimulation();
-    print("velocity=$velocity");
     Simulation simulation = scrollBehavior.release(scrollOffset, velocity);
     if (simulation != null)
       _animation.start(simulation);
   }
 
   void _tickScrollOffset(double value) {
     scrollTo(value);
   }
 
   void _handlePointerDown(_) {
@@ skipping 18 matching lines @@
 
   void _handleFlingCancel(sky.GestureEvent event) {
     settleScrollOffset();
   }
 
   void _handleWheel(sky.WheelEvent event) {
     scrollBy(-event.offsetY);
   }
 
 }