While rolling ANGLE forward in Issue 209689, a few preexisting bugs were uncovered in the VideoTextureCopierCV and its GL context usage that should be fixed separately, so that the ANGLE roll is completely self-contained. Also, changes to ANGLE's commit ID generation necessitated fixes to the ANGLE roll script, which would ideally also be separated in case of a revert of the ANGLE roll.
Created attachment 395331 [details] Patch
Note that there are important steps to take when updating ANGLE. See http://trac.webkit.org/wiki/UpdatingANGLE
Committed r259482: <https://trac.webkit.org/changeset/259482> All reviewed patches have been landed. Closing bug and clearing flags on attachment 395331 [details].
<rdar://problem/61270228>