The test will help cover a bug that I found when doing the refactor
of gl::Program.

BUG=angleproject:1123

Change-Id: Id353ffaffef83ad1538580ad01668c915bf9853f
Reviewed-on: https://chromium-review.googlesource.com/297031Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>