[skottie] Fix sphere lighting shader

Clamp s_base to avoid negative pow arguments.

Fixes rendering issues on Mac/Win.

Change-Id: I5176ffa6150ec430c2ab72115b74fd7ede5f5934
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/369482
Commit-Queue: Florin Malita <fmalita@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Florin Malita <fmalita@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed