[w3c/screen-orientation] Event firing needs fixes (#93)

"Fire a simple event" has been removed. Instead just use [fire an event](https://dom.spec.whatwg.org/#concept-event-fire).

Also, very importantly, since you are firing the events from asynchronous browser code, you need to specify which constructor you are using. So e.g.

> "[Fire an event] named `change` at _doc_'s `screen.orientation` object, using the `Event` constructor from _doc_'s [relevant Realm]"

/cc @annevk @bzbarsky 

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/screen-orientation/issues/93