Change visitProxies signature

There is a perf regression (mainly on the Nexus5) for the https://skia-review.googlesource.com/c/skia/+/46200 (Add method to iterate over a GrOp's GrSurfaceProxies)

This is one candidate.

Change-Id: I995d3a88bad2a914f24b49512abbf01aeaf579c8
Reviewed-on: https://skia-review.googlesource.com/46586
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
32 files changed