The new spec. has changed the name of the 'height' attribute to 'lines', see https://w3c.github.io/webvtt/#region-settings.
Created attachment 350448 [details] Patch
<rdar://problem/44695428>
Comment on attachment 350448 [details] Patch Thanks for reviewing!
Comment on attachment 350448 [details] Patch Clearing flags on attachment: 350448 Committed r236403: <https://trac.webkit.org/changeset/236403>
All reviewed patches have been landed. Closing bug.