The latest spec removed it. https://www.w3.org/Bugs/Public/show_bug.cgi?id=16764
Created attachment 146234 [details] Patch
Comment on attachment 146234 [details] Patch Clearing flags on attachment: 146234 Committed r120797: <http://trac.webkit.org/changeset/120797>
All reviewed patches have been landed. Closing bug.