Implement compile-time optimization for sqrt(constant).

Change-Id: I3427fbaf57787c3051db95ec5882c9292d7985cf
Bug: skia:12034
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/411312
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
9 files changed