If shader is not using yflip, don't get into driver to ask for a new
pipeline program just because yflip has changed. Instead try to use
the non-yflipped program.

Bug: b/173461931
Change-Id: If938f5dc0632529c4f5e477fcb0c67bf58a1f3d0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2549538Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Charlie Lao <cclao@google.com>