https://html.spec.whatwg.org/#reactivate-a-document 4.3 doesn't match implementations, visibilityState isn't always set to 'visible'

### What is the issue with the HTML Standard?

If a page is in a background tab and comes out of bfcache, visibility doesn't automatically change to "visible". Firefox and Chrome dispatch a single visibilitychange event and state is "hidden". Webkit on linux dispatches two events, and state is in both cases "hidden".