Expand modulate, add, subtract, extract component glsl helpers.

src/gpu/GrAARectRenderer.cpp

Index: src/gpu/GrAARectRenderer.cpp
===================================================================
--- src/gpu/GrAARectRenderer.cpp	(revision 8735)
+++ src/gpu/GrAARectRenderer.cpp	(working copy)
@@ -100,7 +100,7 @@
                     fsWidthHeightName);
 
             SkString modulate;
-            GrGLSLModulate4f(&modulate, inputColor, "coverage");
+            GrGLSLModulatef<4>(&modulate, inputColor, "coverage");
             builder->fsCodeAppendf("\t%s = %s;\n", outputColor, modulate.c_str());
         }