anchor.diff:    void _show() {
       _stopHiding();
       _domService.scheduleRead(() {
  -      if (_initialWritePending || _element.classes.contains(_hiddenClass)) {
  +      if (_initialWritePending ||
  +          _element.classes.contains(_hiddenClassLegacy) ||
  +          _element.classes.contains(_hiddenClass)) {
           _domService.scheduleWrite(() {
  +          _element.classes.remove(_hiddenClassLegacy);
             _element.classes.remove(_hiddenClass);
           });
           // remove the ng-hide class in the next event loop, so that effects of
  -        // removing ng-hidden can settle (like changing display from none to
  -        // block)
  +        // removing acx-showhide-hidden can settle (like changing display from
  +        // none to block)
           _domService.nextFrame.then((_) {
             _removeNgHide();
           });
  
positive.code:     } else {
        _initialWritePending = true;
        _domService.scheduleWrite(() {
          _element.classes.toggle(_hideClass, !value);
          _element.classes.toggle(_hiddenClass, !value);
          _initialWritePending = false;
        });
  
negative.code:   void _hide() {
      _hiding = true;
      _domService.scheduleWrite(() {
        _element.classes.add(_hideClassLegacy);
        _element.classes.add(_hideClass);
        _onHide.add(_element);
      });
  