These were already being signaled in the front end.

Bug: angleproject:2763
Change-Id: Id78d3d764e80e687c29c08395b59048d314bfbe2
Reviewed-on: https://chromium-review.googlesource.com/1204490Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>