It was used along with DRT. Since we have stopped support WK1/DRT, it won't be needed.
<rdar://problem/17418584>
Created attachment 233606 [details] patch
Comment on attachment 233606 [details] patch Clearing flags on attachment: 233606 Committed r170342: <http://trac.webkit.org/changeset/170342>
All reviewed patches have been landed. Closing bug.