anchor.diff:          KeyboardHandlerMixin,
           ActivateItemOnKeyPressMixin<T>,
           ShiftClickSelectionMixin<T>
  -    implements PopupSizeProvider, OnChanges, OnDestroy {
  +    implements PopupSizeProvider, AfterChanges, OnDestroy {
     /// Function for use by NgFor for optionGroup.
     ///
     /// Avoids recreating the DOM for the optionGroup.
  
positive.code:   String _ariaActiveDescendant;
  
    final ChangeDetectorRef _changeDetector;
  
    MaterialDropdownSelectComponent(
        @Optional() IdGenerator idGenerator,
  
negative.code:   }
  
    @override
    void ngAfterChanges() {
      if (_disabledChanged && disabled) {
        close();
      }
      _disabledChanged = false;
    }
  
    @override
    void ngOnDestroy() {
      _optionsListener?.cancel();
      _selectionListener?.cancel();
    }
  