function stopWatchingForValueChange() {
  if (!activeElement) {
    return;
  }

  // delete restores the original property definition
  delete activeElement.value;
  activeElement.detachEvent('onpropertychange', handlePropertyChange);

  activeElement = null;
  activeElementID = null;
  activeElementValue = null;
  activeElementValueProp = null;
}
(For old IE.) Removes the event listeners from the currently-tracked element,
if any exists.