Revert "Revert "Revert "Switched highp float to highfloat and mediump float to half."""

This reverts commit 05d5a13fea6246648de7e41358ed338d53c85ea2.

Reason for revert: looks like it broke filterfastbounds

Original change's description:
> Revert "Revert "Switched highp float to highfloat and mediump float to half.""
> 
> This reverts commit 1d816b92bb7cf2258007f3f74ffd143b89f25d01.
> 
> Bug: skia:
> Change-Id: I388b5e5e9bf619db48297a80c9a80c039f26c9f1
> Reviewed-on: https://skia-review.googlesource.com/46464
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

TBR=bsalomon@google.com,ethannicholas@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: skia:
Change-Id: Iddf6aef2ab084aa73da7ceebdfc303a1d2b80cde
Reviewed-on: https://skia-review.googlesource.com/47441
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
132 files changed