This extension is a subset of GL_ARB_provoking_vertex without the
QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION query.

Bug: angleproject:2829
Change-Id: I907a4d16b7b13d3bbfb948842091eedd7b6a8b77
Reviewed-on: https://chromium-review.googlesource.com/c/1410289
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>