remove negate()

negate(x) -> -x

Change-Id: I920b1abe473325309562ca29be6384bedd7e6a42
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/280317
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
2 files changed