Makes it consistent with the other back-end types.

Bug: angleproject:5076 
Change-Id: I7a54dd4a0a54e6dc05e257b7b2ac1ec21ceea700
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2420748
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>