setAssistiveWindowProperties method
Shows/Hides an assistive window with the given properties.
returns Called when the operation completes.
Implementation
Future<bool> setAssistiveWindowProperties(
    SetAssistiveWindowPropertiesParameters parameters) async {
  var $res = await promiseToFuture<bool>(
      $js.chrome.input.ime.setAssistiveWindowProperties(parameters.toJS));
  return $res;
}