NSWindow does some interesting things when a window that's being deallocated is still the key window. Our code for key window management that was added for gamepad testing makes it so that the window remains the key one until after dealloc, which results in a deadlock.
Created attachment 371065 [details]
Comment on attachment 371065 [details]
Clearing flags on attachment: 371065
Committed r245975: <https://trac.webkit.org/changeset/245975>
All reviewed patches have been landed. Closing bug.