This makes interoperation with Chromium tests easier. For instance when
triggering tests with scripts when using sharding. And also using the
run/ wrapper scripts instead of run_gtest_angle_test.

Bug: angleproject:5158
Change-Id: Ia5b1f94c02a081caf576615175791fff4e0d3fb3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2464030Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>