While r174261 fixing build break, there is mistake that flush contents layer instead of overlay layer.
Created attachment 256824 [details] Patch
Comment on attachment 256824 [details] Patch As we talked with this issue, I did mistake in r174261. Thank you for fixing !
Comment on attachment 256824 [details] Patch Clearing flags on attachment: 256824 Committed r186833: <http://trac.webkit.org/changeset/186833>
All reviewed patches have been landed. Closing bug.