It was originally put there to avoid making Structure bigger, but we have a few spare bits in Structure so it would be nice to remove this hack.
Created attachment 232956 [details] Patch
Comment on attachment 232956 [details] Patch Clearing flags on attachment: 232956 Committed r169903: <http://trac.webkit.org/changeset/169903>
All reviewed patches have been landed. Closing bug.