This was added for Chromium in http://trac.webkit.org/changeset/120613, but isn't used at all (as far as I can tell) for other ports. Since it appears to be dead code, we should remove it.
Created attachment 272269 [details]
Comment on attachment 272269 [details]
Clearing flags on attachment: 272269
Committed r197171: <http://trac.webkit.org/changeset/197171>
All reviewed patches have been landed. Closing bug.