This argument isn't used and is in the process of being removed.
We need to remove it partially to unblock landing ANGLE tests in
Chrome. We can follow up later to remove it from the argument set.

Bug: angleproject:3162
Change-Id: I3f80eb1bc14fd93a2b6d9732e51f49873fabb27e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2441512
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>