Remove support for GL discards

src/gpu/vk/GrVkSampler.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "GrVkSampler.h"
 
 #include "GrTextureAccess.h"
 #include "GrVkGpu.h"
 
 static inline VkSamplerAddressMode tile_to_vk_sampler_address(SkShader::TileMode tm) {
     static const VkSamplerAddressMode gWrapModes[] = {
         VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE,
         VK_SAMPLER_ADDRESS_MODE_REPEAT,
         VK_SAMPLER_ADDRESS_MODE_MIRRORED_REPEAT
     };
     GR_STATIC_ASSERT(SkShader::kTileModeCount == SK_ARRAY_COUNT(gWrapModes));
     GR_STATIC_ASSERT(0 == SkShader::kClamp_TileMode);
     GR_STATIC_ASSERT(1 == SkShader::kRepeat_TileMode);
     GR_STATIC_ASSERT(2 == SkShader::kMirror_TileMode);
     return gWrapModes[tm];
 }
 
-GrVkSampler* GrVkSampler::Create(const GrVkGpu* gpu, const GrTextureParams& params, 
+GrVkSampler* GrVkSampler::Create(const GrVkGpu* gpu, const GrTextureParams& params,
                                  uint32_t mipLevels) {
 
     static VkFilter vkMinFilterModes[] = {
         VK_FILTER_NEAREST,
         VK_FILTER_LINEAR,
         VK_FILTER_LINEAR
     };
     static VkFilter vkMagFilterModes[] = {
         VK_FILTER_NEAREST,
         VK_FILTER_LINEAR,
@@ skipping 51 matching lines @@
     key |= (params.getTileModeX() << kTileModeXShift);
 
     GR_STATIC_ASSERT(SkShader::kTileModeCount <= 4);
     key |= (params.getTileModeY() << kTileModeYShift);
 
     SkASSERT(mipLevels < 1024);
     key |= (mipLevels << kMipLevelShift);
 
     return key;
 }