Using the new vertex format type enum, we can shrink the size
of the input layout tables and reduce draw call overhead
further.

BUG=angleproject:959

Change-Id: Iea595fa64edbbd91f669138dfdeb9d2543b83929
Reviewed-on: https://chromium-review.googlesource.com/277291Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>