Simplify translation calculation for mustRegenerate

Change-Id: Ie3545aae753e5ecb45f17c6fefa778c38f9507fe
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264419
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed