Use "clamp" when reexpanding gaussian blurs

Bug: skia:
Change-Id: Ib0a59a56b38eb743f0c78de2cf717d04c775c8df
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/240666
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
1 file changed