Add 'tint' (used by Dawn) to Skia's DEPS

Not used yet (will require some adjustments in Dawn's GN files), but
want to get this in place.

See also: https://skia-review.googlesource.com/c/buildbot/+/347906

Change-Id: I39f632b47a0588c09d17c0f8309158988f061ad2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/348189
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed