allow clip calls w/o op param, remove unnecessary kReplace ops

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2357333002

Review-Url: https://codereview.chromium.org/2357333002
diff --git a/gm/complexclip.cpp b/gm/complexclip.cpp
index fb94957..2f8fa3d 100644
--- a/gm/complexclip.cpp
+++ b/gm/complexclip.cpp
@@ -130,7 +130,7 @@
                                       SkPath::kEvenOdd_FillType);
                     clipB.setFillType(doInvB ? SkPath::kInverseEvenOdd_FillType :
                                       SkPath::kEvenOdd_FillType);
-                    canvas->clipPath(clipA, SkCanvas::kIntersect_Op, fDoAAClip);
+                    canvas->clipPath(clipA, fDoAAClip);
                     canvas->clipPath(clipB, gOps[op].fOp, fDoAAClip);
 
                     // In the inverse case we need to prevent the draw from covering the whole