dEQP-GLES3.functional.rasterization.flatshading.triangles

Bug: angleproject:4070
Change-Id: I8bdba9d1b9d3c04df42a6c90fa106cf7e8b1a018
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1890729Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>