Uses more of the type info table for updates.
Also special-case clamping when uniform count == 1.

Improves the speed of the d3d11 uniform stress test by ~20%.

BUG=angleproject:1390

Change-Id: I6707c67db84c94a28b1519b0bbee5d28fe38b189
Reviewed-on: https://chromium-review.googlesource.com/646828Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>