Remove unused matrix from SlugImpl

Bug: skia:14150
Change-Id: If4a64ae45a5f1de8b02c1ba70864c5358d83a008
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/651419
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed