The log output, specifically in setText was very lacking. This meant manually adding output at the right places (before early returns) and with more information.
Created attachment 139073 [details] Patch
Comment on attachment 139073 [details] Patch Clearing flags on attachment: 139073 Committed r115437: <http://trac.webkit.org/changeset/115437>
All reviewed patches have been landed. Closing bug.