Add arb_texture_rectangle support properly in GLES3 shaders

src/gpu/glsl/GrGLSLFragmentShaderBuilder.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLSLFragmentShaderBuilder_DEFINED
 #define GrGLSLFragmentShaderBuilder_DEFINED
 
@@ skipping 151 matching lines @@
     static const char* DeclaredSecondaryColorOutputName() { return "fsSecondaryColorOut"; }
 
     /*
      * An internal call for GrGLProgramBuilder to use to add varyings to the vertex shader
      */
     void addVarying(GrGLSLVarying*, GrSLPrecision);
 
     void onFinalize() override;
 
     /**
-     * Features that should only be enabled by GrGLSLFragmentShaderBuilder itself.
+     * Features that should only be enabled by GrGLSLFragmentShaderBuilder itself
+     * or its subclass.
      */
     enum GLSLPrivateFeature {
         kFragCoordConventions_GLSLPrivateFeature = kLastGLSLFeature + 1,
         kBlendEquationAdvanced_GLSLPrivateFeature,
         kBlendFuncExtended_GLSLPrivateFeature,
         kExternalTexture_GLSLPrivateFeature,
-        kLastGLSLPrivateFeature = kBlendFuncExtended_GLSLPrivateFeature
+        kRectangleTexture_GLSLPrivateFeature,
+        kLastGLSLPrivateFeature = kRectangleTexture_GLSLPrivateFeature
     };
 
     // Interpretation of FragPosKey when generating code
     enum {
         kNoFragPosRead_FragPosKey           = 0,  // The fragment positition will not be needed.
         kTopLeftFragPosRead_FragPosKey      = 0x1,// Read frag pos relative to top-left.
         kBottomLeftFragPosRead_FragPosKey   = 0x2,// Read frag pos relative to bottom-left.
     };
 
     static const char* kDstTextureColorName;
 
     bool fSetupFragPosition;
     bool fTopLeftFragPosRead;
     int  fCustomColorOutputIndex;
 
     // some state to verify shaders and effects are consistent, this is reset between effects by
     // the program creator
     bool fHasReadDstColor;
     bool fHasReadFragmentPosition;
 
     friend class GrGLSLProgramBuilder;
     friend class GrGLProgramBuilder;
 
     typedef GrGLSLXPFragmentBuilder INHERITED;
 };
 
 #endif