CopyTextureTestES3.ES3UnormFormats/ES3_OpenGL

Bug: angleproject:5127
Change-Id: I93628beb92b8d9b4d8c6f70b32d15ed9add54667
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2446595Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>