It is currently O(n^2), see bug 179950.
Created attachment 327465 [details] patch
Created attachment 327467 [details] patch
Comment on attachment 327467 [details] patch Clearing flags on attachment: 327467 Committed r225102: <https://trac.webkit.org/changeset/225102>
All reviewed patches have been landed. Closing bug.
<rdar://problem/35669758>