r203601 caused crashes in iBooks.
The change made the parameter non-nullable. In ObjC bindings, the approach at the time was to throw an exception (and therefore crash) when passing nil.
Created attachment 293076 [details]
Created attachment 293081 [details]
Comment on attachment 293081 [details]
Clearing flags on attachment: 293081
Committed r208027: <http://trac.webkit.org/changeset/208027>
All reviewed patches have been landed. Closing bug.