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/complexclip3.cpp b/gm/complexclip3.cpp
index fd8cd35..59c78ec 100644
--- a/gm/complexclip3.cpp
+++ b/gm/complexclip3.cpp
@@ -84,7 +84,7 @@
                                                SkPath::kEvenOdd_FillType);
                         secondClip->setFillType(doInvB ? SkPath::kInverseEvenOdd_FillType :
                                                 SkPath::kEvenOdd_FillType);
-                        canvas->clipPath(*firstClip, SkCanvas::kIntersect_Op, doAAA);
+                        canvas->clipPath(*firstClip, doAAA);
                         canvas->clipPath(*secondClip, gOps[op].fOp, doAAB);
 
                         // draw rect clipped