Turns out that NSWindowDidBecomeKeyNotification and NSWindowDidResignKeyNotification do not notify us when a popover becomes key so we need to keep using the SPI I removed.
Created attachment 234654 [details] Partially reverts r167770
Comment on attachment 234654 [details] Partially reverts r167770 Clearing flags on attachment: 234654 Committed r170931: <http://trac.webkit.org/changeset/170931>
All reviewed patches have been landed. Closing bug.