Fix the REPEAT test, and add a D3D11 and OpenGL null test.

BUG=angleproject:1390

Change-Id: I491cbc9f9201ef85aeb9f70138a276078220b26d
Reviewed-on: https://chromium-review.googlesource.com/623928Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>