Construct a KeyEvent with parent as the event we're emulating.
Source
KeyEvent.wrap(KeyboardEvent parent) : super(parent) {
_parent = parent;
_shadowAltKey = _realAltKey;
_shadowCharCode = _realCharCode;
_shadowKeyCode = _realKeyCode;
_currentTarget =
_parent.currentTarget == null ? window : _parent.currentTarget;
}