Also fixes the uniform count upper limit in glGetActiveUniformsiv.

BUG=angleproject:507

Change-Id: Icfc90ed64cf94b1bab2d4cc93a8fb5e11b28d666
Reviewed-on: https://chromium-review.googlesource.com/261874Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>