[fullscreen] Clarify "except for the current top element" in "fully exit fullscreen" (#10)

https://fullscreen.spec.whatwg.org/#fully-exit-fullscreen

The "top" in step 3 could be taken to mean the element at the top of the top layer stack, but presumably it means to leave only the topmost element with the fullscreen flag set.

The end result could be slightly strange, visually at least, if there was a modal dialog at the top of the top layer stack inside an iframe, where after exiting fullscreen that dialog is still showing inside an iframe. This is probably OK, though.

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fullscreen/issues/10