Revert "Add GrRenderTargetContext instantiate & asTextureProxy"

This reverts commit 9113edfff89e657dabc0ba095c54f7720550196c.

Reason for revert: Looks to be causing EXCEPTION_ACCESS_VIOLATION:

https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Win-MSVC-NUC-GPU-IntelIris6100-x86_64-Debug/builds/121/steps/test_skia%20on%20Windows/logs/stdio
https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Win-MSVC-GCE-CPU-AVX2-x86-Debug/builds/2384/steps/test_skia%20on%20Windows-2008ServerR2-SP1/logs/stdio
https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Win-MSVC-ShuttleC-GPU-iHD530-x86_64-Debug/builds/785/steps/test_skia%20on%20Windows/logs/stdio

Original change's description:
> Add GrRenderTargetContext instantiate & asTextureProxy
> 
> This CL also centralizes the instantiation code in GrSurfaceProxy and adds a test.
> 
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4494
> 
> Change-Id: I0081d9a216dc0af293179f23bcb88acf6a822324
> Reviewed-on: https://skia-review.googlesource.com/4494
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> 

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

Change-Id: I225ce7867ebd445067e5ea55ebbfd587f7fe782a
Reviewed-on: https://skia-review.googlesource.com/4528
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
11 files changed