Cannot use `EventStreamProvider` because `ElementStream` is not published.

[ditman]

I'm trying to listen to the cancel event of an HTMLInputElement, and instead of using the .oncancel setter directly:

• web/lib/src/dom/html.dart

  Lines 499 to 500 in 51e594b

  	external set oncancel(EventHandler value);
  	external EventHandler get oncancel;

I'm trying to add an onCancel stream to an web.HTMLInputElement with something like the following:

extension AddOnCancelStreamToInputElement on web.HTMLInputElement {
  web.ElementStream<web.Event> get onCancel => const
    web.EventStreamProvider<web.Event>('cancel').forElement(this);
}

However, I get the following error:

Undefined class 'ElementStream'.
Try changing the name to the name of an existing class, or creating a class with the name 'ElementStream'. dart(undefined_class)

2 questions here:

1. Can an onCancel Stream be added to the HTMLInputElement class somewhere here.
2. and/or expose the ElementStream<T> so I can add my own with the same helpers available for package:web.

[ditman]

(Am I supposed to use this differently, though?)

[CEksal]

If you don't need to use ElementStream#capture, you can use Stream<web.Event> instead (since ElementStream<web.Event> implements that interface).