Program: Sampler uniform query in front-end. We have this information stored in the front-end sampler bindings. This solves sampler uniform query across the various back-ends. Turns on a bunch of uniform_api dEQP tests. Bug: angleproject:2612 Change-Id: If8752a26438595ad103598369df360e2f5e12d53 Reviewed-on: https://chromium-review.googlesource.com/1101572 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Luc Ferron <lucferron@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>