Simplify the implementation of ANGLE_INSTANTIATE_TEST I mistakenly submitted a refactor with +2 but not +1 so a comment wasn't addressed, hopefully fixes it. BUG=angleproject:892 Change-Id: I096c2424449be196dfa949cc6ef662b766036330 Reviewed-on: https://chromium-review.googlesource.com/272905 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>