This is to avoid wrong native level in Metal, for example, not taking
into account the OpenGL base level.

Bug: angleproject:2634
Change-Id: I3a7a3ac41bdbd91a47755bb4ca11bd579c182e04
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2433326
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>