This was fixed with https://bugs.webkit.org/show_bug.cgi?id=101464. The fix is no more valid as we create the surface during the first update. We need something similar to avoid this situation.
Created attachment 180153 [details] patch
Comment on attachment 180153 [details] patch Clearing flags on attachment: 180153 Committed r138154: <http://trac.webkit.org/changeset/138154>
All reviewed patches have been landed. Closing bug.