Segfault in QtWebKit bisects to GC change

I'm running into this issue in my PyQt app. Here's my tracking bug: https://github.com/oconnor663/fbmessenger/issues/45

My app crashes with a segfault if I do a lot of user activity in one of my WebViews. Here are the details of the crash in gdb: https://gist.github.com/oconnor663/8483257 (Edit, slightly better stacktrace: https://gist.github.com/oconnor663/9077080) My stacktrace there is full of "??", though I'm not experienced enough with gdb to know why. The crash only repros after the app has been running for exactly 1 minute. I'm able to bisect the crash to this WebKit change: http://trac.webkit.org/changeset/141114 "Implement GCActivityCallback". Before that change, it never repros. At that change, it repros 100% of the time.

Detailed repro steps for my app are in that GitHub issue. Please let me know if there's any more gdb information I could provide.