Revert "Add IORef capability to GrSurfaceProxy objects"

Revert "Add IORef capability to GrSurfaceProxy objects"

This reverts commit 286b96f876953c94c178e3abbeb4eab186ad1fef.

Reason for revert:

Failure on Mac Mini:

FAILURE: ../../../tests/ProxyRefTest.cpp:59	proxy->getPendingWriteCnt_TestOnly() == expectedNumWrites

../../../tests/ProxyRefTest.cpp:64: fatal error: "assert(proxy->getPendingWriteCnt_TestOnly() == expectedNumWrites)"

Original change's description:
> Add IORef capability to GrSurfaceProxy objects
>
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4734
>
> Change-Id: If10fbe555e9fa3331bfa01065028e1afe82adb78
> Reviewed-on: https://skia-review.googlesource.com/4734
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
>

TBR=bsalomon@google.com,robertphillips@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I5e1c201e027d4e9687b01f28a418b1884d3f9ece
Reviewed-on: https://skia-review.googlesource.com/4776
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>