SkScalarMul is deprecated

BUG=skia:

Change-Id: I88ecfe9d4c72506f6b1a0e0dfadd2a5c171a6cb6
Reviewed-on: https://skia-review.googlesource.com/8353
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
diff --git a/src/gpu/ops/GrAAStrokeRectOp.cpp b/src/gpu/ops/GrAAStrokeRectOp.cpp
index c30be77..25f5071 100644
--- a/src/gpu/ops/GrAAStrokeRectOp.cpp
+++ b/src/gpu/ops/GrAAStrokeRectOp.cpp
@@ -58,8 +58,8 @@
 
     const SkScalar dx = devStrokeSize.fX;
     const SkScalar dy = devStrokeSize.fY;
-    const SkScalar rx = SkScalarMul(dx, SK_ScalarHalf);
-    const SkScalar ry = SkScalarMul(dy, SK_ScalarHalf);
+    const SkScalar rx = SkScalarHalf(dx);
+    const SkScalar ry = SkScalarHalf(dy);
 
     *devOutside = devRect;
     *devOutsideAssist = devRect;