anchor.diff:    //
     // If it has a parent, we should re-show it.
     void _hideModalOverlay({bool temporary = false}) {
  -    _restoreFocus();
       if (!temporary) {
  +      _restoreFocus();
         if (_stack != null) {
           _stack.onModalClosed(this);
         } else if (_parentModal != null) {
  
positive.code:   Future<bool> _pendingOpen;
    Future<bool> _pendingClose;
  
    ModalComponent(OverlayService overlayService, this._element, this._ngZone,
        @Optional() @SkipSelf() this._parentModal, @Optional() this._stack) {
      _createdOverlayRef(
          overlayService.createOverlayRefSync(OverlayState.Dialog));
  
negative.code:   //
    // If it has a parent, we should temporarily hide it.
    void _showModalOverlay({bool temporary = false}) {
      if (!temporary) {
        _saveFocus();
        if (_stack != null) {
          _stack.onModalOpened(this);
        } else if (_parentModal != null) {
  