Revert "Add integer texture support."

Revert "Add integer texture support."

This reverts commit 434c534bd0ec08cb355fecfb6d2110197b523e74.

Reason for revert: Undefined behavior. From

https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Ubuntu-Clang-Golo-GPU-GT610-x86_64-Debug-ASAN/builds/1272/steps/test_skia%20on%20Ubuntu/logs/stdio

../../../tests/IntTextureTest.cpp:51:44: runtime error: left shift of negative value -1
    #0 0x2257480 in test_IntTexture(skiatest::Reporter*, sk_gpu_test::ContextInfo const&) (/b/swarm_slave/w/ir0aO1sa/out/Debug/dm+0x2257480)
    #1 0x1ca1066 in skiatest::RunWithGPUTestContexts(void (*)(skiatest::Reporter*, sk_gpu_test::ContextInfo const&), bool (*)(sk_gpu_test::GrContextFactory::ContextType), skiatest::Reporter*, sk_gpu_test::GrContextFactory*) (/b/swarm_slave/w/ir0aO1sa/out/Debug/dm+0x1ca1066)
    #2 0x1ca080d in run_test(skiatest::Test) (/b/swarm_slave/w/ir0aO1sa/out/Debug/dm+0x1ca080d)
    #3 0x1c9e5e9 in dm_main() (/b/swarm_slave/w/ir0aO1sa/out/Debug/dm+0x1c9e5e9)
    #4 0x7f2d2ba8df44 in __libc_start_main /build/eglibc-oGUzwX/eglibc-2.19/csu/libc-start.c:287
    #5 0x1bb3028 in _start (/b/swarm_slave/w/ir0aO1sa/out/Debug/dm+0x1bb3028)

SUMMARY: AddressSanitizer: undefined-behavior ../../../tests/IntTextureTest.cpp:51:44 in
step returned non-zero exit code: 1

Original change's description:
> Add integer texture support.
>
> This allows us to create integer textures and sample them from a GrProcessor's code.
>
> Filtering is limited to NEAREST.
>
> Adds tests for reading/writing pixels, copying, and drawing. These operations are not allowed to convert to fixed/float configs.
>
> Vulkan support is TBD.
>
>
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4348
>
> Change-Id: If38d89a03285d4bd98d1f14f9638b0320977e43d
> Reviewed-on: https://skia-review.googlesource.com/4348
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Chris Dalton <csmartdalton@google.com>
>

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

Change-Id: I39f1a0a0dd3e6cde1143c8cc1217d2e3d5977b21
Reviewed-on: https://skia-review.googlesource.com/4663
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>