The uniforms check was not correctly validating vector count instead
of uniform count. Fix this, and reduce the maximum maxtrix uniforms
to fix a crash on the perf bots.

BUG=angleproject:1385
BUG=angleproject:1390
BUG=angleproject:1671

Change-Id: I261477c33639ed516ff6a29b38ab87f89309a7f1
Reviewed-on: https://chromium-review.googlesource.com/422533Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>