re-re-land of skslc now automatically turns on derivatives support

src/gpu/glsl/GrGLSLFragmentShaderBuilder.h

Index: src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
diff --git a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
index 6a4a18482932ccfc78a27a825f4b4b0bf9f95e27..bf8569c073ecb47f94dd1b0a9817c08c0efc9433 100644
--- a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
+++ b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
@@ -29,8 +29,7 @@ public:
      * if code is added that uses one of these features without calling enableFeature()
      */
     enum GLSLFeature {
-        kStandardDerivatives_GLSLFeature = kLastGLSLPrivateFeature + 1,
-        kPixelLocalStorage_GLSLFeature,
+        kPixelLocalStorage_GLSLFeature = kLastGLSLPrivateFeature + 1,
         kMultisampleInterpolation_GLSLFeature
     };