Enables a bunch of self-tests.

Bug: angleproject:5530
Change-Id: Idd14574ba0f3d44124e153ccb32fec7318baf217
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2647745Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>