Stop supporting HW dither

src/gpu/gl/GrGLGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLGpu_DEFINED
 #define GrGLGpu_DEFINED
 
@@ skipping 216 matching lines @@
         int                         fCount;
         unsigned int                fCurrLRUStamp;
         GrGLGpu*                    fGpu;
 #ifdef PROGRAM_CACHE_STATS
         int                         fTotalRequests;
         int                         fCacheMisses;
         int                         fHashMisses; // cache hit but hash table missed
 #endif
     };
 
-    void flushDither(bool dither);
     void flushColorWrite(bool writeColor);
     void flushDrawFace(GrPipelineBuilder::DrawFace face);
 
     // flushes the scissor. see the note on flushBoundTextureAndParams about
     // flushing the scissor after that function is called.
     void flushScissor(const GrScissorState&,
                       const GrGLIRect& rtViewport,
                       GrSurfaceOrigin rtOrigin);
 
     // disables the scissor
@@ skipping 234 matching lines @@
     } fCopyProgram;
 
     TriState fMSAAEnabled;
 
     GrStencilSettings           fHWStencilSettings;
     TriState                    fHWStencilTestEnabled;
 
 
     GrPipelineBuilder::DrawFace fHWDrawFace;
     TriState                    fHWWriteToColor;
-    TriState                    fHWDitherEnabled;
     uint32_t                    fHWBoundRenderTargetUniqueID;
     TriState                    fHWSRGBFramebuffer;
     SkTArray<uint32_t, true>    fHWBoundTextureUniqueIDs;
 
     ///@}
 
     // Mapping of pixel configs to known supported stencil formats to be used
     // when adding a stencil buffer to a framebuffer.
     int fPixelConfigToStencilIndex[kGrPixelConfigCnt];
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };
 
 #endif