anchor.diff:        if (content == null)
           continue;
         String key = historyEntry.route.key;
  -      Transition transition = new Transition(content: content, key: key)
  -        ..direction = (i <= state.historyIndex) ? TransitionDirection.forward : TransitionDirection.reverse
  -        ..interactive = (i == state.historyIndex)
  -        ..onDismissed = () {
  -        setState(() {
  -          state.history.remove(historyEntry);
  -        });
  -      };
  +      Transition transition = new Transition(
  +        key: key,
  +        content: content,
  +        direction: (i <= state.historyIndex) ? TransitionDirection.forward : TransitionDirection.reverse,
  +        interactive: (i == state.historyIndex),
  +        onDismissed: () {
  +          setState(() {
  +            state.history.remove(historyEntry);
  +          });
  +        }
  +      );
         visibleRoutes.add(transition);
       }
       return new Stack(visibleRoutes);
  
positive.code:   AnimationPerformance _performance;
  
    void initState() {
      _position = new AnimatedType<Point>(_kTransitionStartPoint)
        ..end = Point.origin
        ..curve = easeOut;
      _opacity = new AnimatedType<double>(0.0, end: 1.0)
        ..curve = easeOut;
      _performance = new AnimationPerformance()
  
negative.code:       direction = source.direction;
        _start();
      }
      interactive = source.interactive;
      onDismissed = source.onDismissed;
      super.syncFields(source);
    }
  