Break dependency of AnimationPerformance on AnimatedValue

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/base/lerp.dart';
 import 'package:sky/painting/text_style.dart';
@@ skipping 11 matching lines @@
 const double _kDismissCardThreshold = 0.70;
 
 class CardCollectionApp extends App {
 
   final TextStyle cardLabelStyle =
     new TextStyle(color: White, fontSize: 18.0, fontWeight: bold);
 
   CardCollectionApp() {
     _activeCardAnimation = new AnimationPerformance()
       ..variable = new AnimatedType(0.0, 1.0)
-      ..duration = new Duration(milliseconds: _kCardDismissFadeoutMS);
-    _activeCardAnimation.timeline.onValueChanged.listen(_handleAnimationProgressChanged);
+      ..duration = new Duration(milliseconds: _kCardDismissFadeoutMS)
+      ..addListener(_handleAnimationProgressChanged);
   }
 
   int _activeCardIndex = -1;
   double _activeCardAnchorX;
   AnimationPerformance _activeCardAnimation;
   double _activeCardWidth;
   bool _activeCardDragUnderway = false;
   Set<int> _dismissedCardIndices = new Set<int>();
 
   double get _activeCardOpacity => 1.0 - _activeCardAnimation.progress;
 
   double get _activeCardOffset {
     return _activeCardAnimation.progress * _activeCardWidth * _kDismissCardThreshold;
   }
 
-  void _handleAnimationProgressChanged(_) {
+  void _handleAnimationProgressChanged() {
     setState(() {
       if (_activeCardAnimation.isCompleted && !_activeCardDragUnderway)
         _dismissedCardIndices.add(_activeCardIndex);
     });
   }
 
   void _handleSizeChanged(Size newSize) {
     _activeCardWidth = newSize.width;
   }
 
@@ skipping 97 matching lines @@
       body: _buildCardCollection(
           [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])
     );
   }
 }
 
 void main() {
   runApp(new CardCollectionApp());
 }