@Override
 public void setAriaGrabbedState(Element element, BooleanAndUndefined value) {
   State.GRABBED.set(element, value);
 }
 @Override
 public String getAriaGrabbedState(Element element) {
   return State.GRABBED.get(element);
 }
 @Override
 public void removeAriaGrabbedState(Element element) {
   State.GRABBED.remove(element);
 }