Unable to Dispatch KeyEvents

[psygo]

I've originally posted about this topic in this SO question

Dispatching KeyboardEvents seems fine, but, ideally, I would rather use the richer KeyEvent, in order to make testing much easier.

Whenever I try to dispatch an event with, for example:

document.body.dispatchEvent(KeyEvent('keypress', keyCode: 65, charCode: 97));

I get

Error: Failed to execute 'dispatchEvent' on 'EventTarget': parameter 1 is not of type 'Event'.

I don't get why this happens, because a KeyEvent implements a KeyboardEvent, which is an Event.

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Also, I don't get why the docs tell us to add to a Stream, when that is in fact not possible, or is it? — the add method is only supported if we are working with, for example, a Sink or a StreamController.

[psygo]

I've ended up posting about this on reddit as well.