A test is added that dispatches a large number of vertex shaders,
generating primitives that are all culled.  The vertex shaders are
simple so that code injected for pre-rotation would make up the majority
of the shader code.

Bug: angleproject:5478
Change-Id: I75092cb25e6427449251985f56e54f89813dec32
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2615821Reviewed-by: Charlie Lao <cclao@google.com>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>