Don't overflow tile calculation
Don't overflow tile calculation

Bug: chromium:1299266
Change-Id: Ic3d0f5e96c9c1d3d0b50cc20b41143481cdbb042
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/519324
Reviewed-by: Robert Phillips <95e8ac5504948c7bf91b22c16a8dbb7ae7c66bfd@google.com>
Commit-Queue: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>

google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia