Reviewed by Darin Adler.

        REGRESSION (full screen video): Watch Again button is obscured after full screen playback ends at Apple trailers page
        https://bugs.webkit.org/show_bug.cgi?id=62507

        No new tests; DRT would have to be modified to delay between receiving exitFullScreenForElement() and calling
        webkitWillExitFullScreenForElement() to be able to test this.

        If the full-screen element is removed, and webkitWillExitFullScreenForElement() is not called before
        fullScreenElementRemoved() returns, then ancestors of the full-screen element will not have their
        containsFullScreenElement property removed.  To protect against this, reset the property by calling
        setContainsFullScreenElementRecursively() from within fullScreenElementRemoved().

        * dom/Document.cpp:
        (WebCore::Document::fullScreenElementRemoved): Added call to setContainsFullScreenElementRecursively.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@88629 268f45cc-cd09-0410-ab3c-d52691b4dbfc