Add missing clone method to GrMorphologyEffect

Change-Id: Id0e435e7f8d055db336e5be80ae1c308197dd950
Reviewed-on: https://skia-review.googlesource.com/28042
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
1 file changed