[skif] Remove legacy DropShadow implementation

Bug: skia:9282
Change-Id: I813d65459d23469e42f0155f4ff517f9dbdb846c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/721820
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
1 file changed