My previous attempt at fixing this crash in <http://trac.webkit.org/changeset/221323> was incorrect, since it is still crashing on the bot(s). The current theory of why this is failing is that the WorkQueue object deletes itself in the middle of the performWorkOnRegisteredWorkThread method when calling deref().
Created attachment 319462 [details] Patch
Comment on attachment 319462 [details] Patch Thanks for reviewing!
Comment on attachment 319462 [details] Patch Clearing flags on attachment: 319462 Committed r221425: <http://trac.webkit.org/changeset/221425>
All reviewed patches have been landed. Closing bug.
<rdar://problem/34693984>