- also enables all dEQP tests for functional.read_pixels.*

Bug: angleproject:2480

Change-Id: Ib7bcd6b046ff8b0ecf110e70f735036bedf17902
Reviewed-on: https://chromium-review.googlesource.com/1058149
Commit-Queue: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>