Enable vertex ID support on Metal

This allows the tessellated stroke renderer to run on Metal.

Change-Id: Ia6bd4008a3310cd316abdc2715efcec3916c6bfa
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/408358
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed