There is a driver bug on Adreno 3xx devices causing incorrect
rendering when flat scalar varyings are used in fragment shaders. The
original report was in bug 1630356, but it has been reported since on
several occasions for various shaders, which have been fixed one at a
time. This patch removes the remaining flat scalar varyings from all
of our shaders so that we do not encounter this issue again.
Additionally, it removes the usage of #ifdefs surrounding these
workarounds so that it applies to all platforms rather than just
android. This has been done to keep the code more readable - now that
we have a test to ensure this is not regressed it no longer needs to
be loud and ugly.
Differential Revision: https://phabricator.services.mozilla.com/D124204
4a11f7cb49