Try to fix colormasking on GLES3 devices.

Not tested, though, since I don't have one... from reporting.
Ensure #extension is before non-# tokens.

As required by Tegra devices from reporting.
Fix shader blending on ARM GLES3 devices.

We currently ban them from GLES3, and this was interacting with that
incorrectly.  Should we still ban them, though?
Merge pull request #6491 from unknownbrackets/gpu-minor

Try to fix color test masking on GLES3 devices