Merge 126043 - webkitfullscreenchange not fired properly in iframe.
Reviewed by Adam Barth.
webkitCancelFullScreen exits fullscreen by invoking webkitExitFullScreen on topDocument.
However, if webkitDidExitFullScreenForElement is invoked on a descendant document, no events
get dispatched. This change starts the event dispatch delay timer on the document where
webkitCancelFullScreen was called, so that the events get dispatched. In addition, when events
are dispatched, the check whether a node has been removed is changed to also check that the
node isn't in another document, as can happen with frames. Finally, webkitExitFullscreen
is fixed to remove unnecessary code and conform to the spec.
No new tests (the existing fullscreen/exit-full-screen-iframe.html test now passes).