I assume it's just hitting an assert. Also see bug 41175.
Created attachment 67395 [details] Patch
Comment on attachment 67395 [details] Patch r=me
Comment on attachment 67395 [details] Patch Clearing flags on attachment: 67395 Committed r67381: <http://trac.webkit.org/changeset/67381>
All reviewed patches have been landed. Closing bug.