Rename `bool highp` to a non-reserved keyword.

We can't name our variables after GLSL keywords. This worked in the past
because our optimizer was able to optimize away `highp`, as it is
always constant.

Change-Id: Idbd97cad4f10da72f610701c83b0736e96a06626
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368419
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed