Add more specialized fragment builders

src/effects/SkColorCubeFilter.cpp

Index: src/effects/SkColorCubeFilter.cpp
diff --git a/src/effects/SkColorCubeFilter.cpp b/src/effects/SkColorCubeFilter.cpp
index 2cbbeb2e8196eb774a93d25c7787df505ba9c626..4ddbc0c30f41a1f19a1bab70d288e381629772b9 100644
--- a/src/effects/SkColorCubeFilter.cpp
+++ b/src/effects/SkColorCubeFilter.cpp
@@ -256,7 +256,7 @@ void GrColorCubeEffect::GLSLProcessor::emitCode(EmitArgs& args) {
     // Note: if implemented using texture3D in OpenGL ES older than OpenGL ES 3.0,
     //       the shader might need "#extension GL_OES_texture_3D : enable".
 
-    GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+    GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
 
     // Unpremultiply color
     fragBuilder->codeAppendf("\tfloat %s = max(%s.a, 0.00001);\n", nonZeroAlpha, args.fInputColor);