Revert "Revert "Allow FPs to elevate default precision for the entire fragment program""

Revert "Revert "Allow FPs to elevate default precision for the entire fragment program""

This reverts commit 903c3f70400462e191ccbca63393b2df3fe2dd11.

Reason for revert: Vulkan issue fixed in compiler.

Original change's description:
> Revert "Allow FPs to elevate default precision for the entire fragment program"
>
> This reverts commit 92d7ccafdf896cf19764e025873d13315a76842d.
>
> Reason for revert: Vulkan errors.
>
> Original change's description:
> > Allow FPs to elevate default precision for the entire fragment program
> >
> > Currently, GrConfigConversionEffect is able to round-trip on many mobile
> > GPUs because it uses highp for all intermediate variables (including the
> > texture fetch result). Separating the texture sample into a different
> > processor breaks that.
> >
> > This is a blunt instrument, not to be used lightly.
> >
> > Bug: skia:
> > Change-Id: I2ab365e3da79628069e2eb727c43c2bf45bfd789
> > Reviewed-on: https://skia-review.googlesource.com/10162
> > Reviewed-by: Brian Salomon <bsalomon@google.com>
> > Commit-Queue: Brian Osman <brianosman@google.com>
> >
>
> TBR=bsalomon@google.com,robertphillips@google.com,brianosman@google.com,ethannicholas@google.com,reviews@skia.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
>
> Change-Id: Iee5bb409f86a9cabecc76bd1273a5b3cef6af179
> Reviewed-on: https://skia-review.googlesource.com/10967
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>
>

TBR=bsalomon@google.com,robertphillips@google.com,reviews@skia.org,brianosman@google.com,ethannicholas@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I733a0ecc40b58d8727f0259b5498c8e6610cedce
Reviewed-on: https://skia-review.googlesource.com/11010
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>