guard to remove DrawBitmapRectFlags

BUG=skia:

Review URL: https://codereview.chromium.org/1235393003
diff --git a/bench/BitmapRectBench.cpp b/bench/BitmapRectBench.cpp
index d3a7574..596c18f 100644
--- a/bench/BitmapRectBench.cpp
+++ b/bench/BitmapRectBench.cpp
@@ -96,7 +96,7 @@
         paint.setAlpha(fAlpha);
 
         for (int i = 0; i < loops; i++) {
-            canvas->drawBitmapRectToRect(fBitmap, &fSrcR, fDstR, &paint);
+            canvas->drawBitmapRect(fBitmap, &fSrcR, fDstR, &paint);
         }
     }