Vulkan:Only apply invariant pragma to output vars The "#pragma STDGL invariant(all)" directive should only be applied to shader output vars. This change also removes the workaround SH_DONT_REMOVE_INVARIANT_FOR_FRAGMENT_INPUT which is no longer needed. This change fixes two tests that were incorrectly assuming that the pragma would be applied to inputs: GLSLTest.InvariantAll[Both|In]. Bug: angleproject:1293 Bug: angleproject:3285 Change-Id: I4eb03fa89fbc7c560150ee0cc32382024b0cb3e3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1558678 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tobin Ehlis <tobine@google.com> Commit-Queue: Tobin Ehlis <tobine@google.com>