fix for uniform view matrix being uploaded but not used

As discussed, I'll follow this up by removing localmatrix/uniform view matrix from the base classe

BUG=skia:

Review URL: https://codereview.chromium.org/920933002
diff --git a/src/gpu/GrAAConvexPathRenderer.cpp b/src/gpu/GrAAConvexPathRenderer.cpp
index f4a6266..6b825e7 100644
--- a/src/gpu/GrAAConvexPathRenderer.cpp
+++ b/src/gpu/GrAAConvexPathRenderer.cpp
@@ -542,12 +542,8 @@
             this->setupColorPassThrough(pb, local.fInputColorType, args.fOutputColor, NULL,
                                         &fColorUniform);
 
-            // setup uniform viewMatrix
-            this->addUniformViewMatrix(pb);
-
             // Setup position
-            SetupPosition(vsBuilder, gpArgs, qe.inPosition()->fName,
-                          qe.viewMatrix(), this->uViewM());
+            this->setupPosition(pb, gpArgs, qe.inPosition()->fName, qe.viewMatrix());
 
             // emit transforms
             this->emitTransforms(args.fPB, gpArgs->fPositionVar, qe.inPosition()->fName,