dispatchEvent method
      
void
dispatchEvent(
    
- Event event
inherited
    event - The event that gets fired.
Fire an event type.
Implementation
void dispatchEvent(Event event) {
  if (_listeners == null || _listeners!.isEmpty) return;
  final listeners = _listeners!;
  final listenerArray = listeners[event.type];
  if (listenerArray != null) {
    event.target = this;
    final array = listenerArray.sublist(0);
    for (int i = 0, l = array.length; i < l; i++) {
      final Function fn = array[i];
      fn(event);
    }
    event.target = null;
  }
}