dillon1000/react

Use only public api for ReactDOMEventListener-test.js (#11327)

* Use only public api for ReactDOMEventListener-test.js

* Use less confusing naming

There was no need to extract React elements into separate variables.

* Replace the "disappearance" test

I could not get it to fail on master so it was probably testing something specific to Stack implementation details. It was also already broken because it didn't look at the right argument and never actually called `unmountComponentAtNode`.

Instead I replaced it with original repro case from https://github.com/facebook/react/issues/1105 which is when it was introduced.

* Tweak naming and add comments

* Missed this one