Based on Nvidia's recommendation that the following:

    all(lessThan(gl_FragCoord.xy, vec2(1.0, 1.0)))

isn't necessarily true for only a single FS invocation, even when not
multisampling.  The tests that do the above are changed to compute
instead.

Bug: angleproject:3831
Change-Id: I22d935f797c2e385218bc6af31e98a7f672a7707
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2012743Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>