It can still be closed, but user experience is quite weird. We should reset autodisplay, but currently cannot, because ether is no page.
Created attachment 85528 [details] proposed fix
Created attachment 85531 [details] patch for landing ASSERT(isMainThread()) that I added was incorrect.
Comment on attachment 85531 [details] patch for landing Clearing flags on attachment: 85531 Committed r80901: <http://trac.webkit.org/changeset/80901>
All reviewed patches have been landed. Closing bug.