Weed out duplicates from the proxy version of addDependency

Change-Id: Ic1c8e0cf2a72c1cac8dadcfb7359dd1356671b11
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/242389
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
1 file changed