Remove tab parameter from GrGLSLMulVarBy4f function

src/effects/SkMorphologyImageFilter.cpp

Index: src/effects/SkMorphologyImageFilter.cpp
diff --git a/src/effects/SkMorphologyImageFilter.cpp b/src/effects/SkMorphologyImageFilter.cpp
index 4c7f62482c64fd9c6330320a6cc82fa443dd4f3e..71a70d6459b8bf31869a5824855f91c5815ca6cf 100644
--- a/src/effects/SkMorphologyImageFilter.cpp
+++ b/src/effects/SkMorphologyImageFilter.cpp
@@ -399,7 +399,7 @@ void GrGLMorphologyEffect::emitCode(GrGLProgramBuilder* builder,
     fsBuilder->codeAppendf("\t\t\tcoord += %s;\n", imgInc);
     fsBuilder->codeAppend("\t\t}\n");
     SkString modulate;
-    GrGLSLMulVarBy4f(&modulate, 2, outputColor, inputColor);
+    GrGLSLMulVarBy4f(&modulate, outputColor, inputColor);
     fsBuilder->codeAppend(modulate.c_str());
 }