Move GetUniform size validation to top layer.

BUG=angle:571

Change-Id: Ie7064cf85f6a125ccd6cdf1bff89443520e2a06d
Reviewed-on: https://chromium-review.googlesource.com/212932
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
4 files changed