Use the dEQP null platform for speed and to avoid popping up
a new window. Store the case lists as .gz files to save space
in the repo.

BUG=angleproject:998

Change-Id: Ib9b10b8a83edc510cc98f120847b1cf93a3d2f78
Reviewed-on: https://chromium-review.googlesource.com/273975Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>