anchor.diff:  
     @override
     void dispose() {
  -    _selection?.unregisterAnimationListener(this);
  +    _selection?.removeAnimationListener(this);
       super.dispose();
     }
   
  
positive.code: 
    /// Calls listener methods every time the value or status of the selection animation changes.
    ///
    /// Listeners can be removed with [unregisterAnimationListener].
    void registerAnimationListener(TabBarSelectionAnimationListener listener) {
      _animationListeners.add(listener);
      _controller
        ..addStatusListener(listener.handleStatusChange)
  
negative.code: 
    @override
    void dispose() {
      _selection?.removeAnimationListener(this);
      super.dispose();
    }
  
  