Thanks to Markus from NVIDIA. This inlines some methods and optimizes
the check if a uniform is a bool type.

BUG=angleproject:2119

Change-Id: I6f2c2d22c577458b39de600d3c56ec8e1a456a7a
Reviewed-on: https://chromium-review.googlesource.com/591699
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>