Remove IO refs from GrSurfaceProxy only

This CL leaves the Ganesh world in a very odd place. In particular it still:
  has pendingIO refs on GrSurfaces
  forwards the proxy refs on to the backing GrSurface

Removing everything at once only ends in a mess thus, this goofball CL.

Change-Id: If112ff311bcef2e8d65a36c3b53b0ded4041c24e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/210040
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
19 files changed