Implement on Windows.
<rdar://problem/24623986>
Created attachment 271521 [details] Proposed patch.
Created attachment 271553 [details] Updated patch
Comment on attachment 271553 [details] Updated patch r=me. I assume MTEnableCaption2015Behavior gets called in other code that you changed previously?
Comment on attachment 271553 [details] Updated patch Clearing flags on attachment: 271553 Committed r196703: <http://trac.webkit.org/changeset/196703>
All reviewed patches have been landed. Closing bug.