This will give us better dashboard encapsulation when we're
running on the Chromium bots. It also paves the way for more
specialized draw call tests, like for indexed draw, with uniform
updates, instancing, etc.

BUG=angleproject:744

Change-Id: I396de28c027f99da18a0904f959d23b59cac2010
Reviewed-on: https://chromium-review.googlesource.com/263505Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>