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

gm/pathopsinverse.cpp

Index: gm/pathopsinverse.cpp
diff --git a/gm/pathopsinverse.cpp b/gm/pathopsinverse.cpp
index 176bc769e24f64211cdd9e758cba8000aeb5bec3..918666ca382b83765a81487f23a2e3b210c78715 100644
--- a/gm/pathopsinverse.cpp
+++ b/gm/pathopsinverse.cpp
@@ -75,7 +75,7 @@ protected:
                 two.addRect(40, 40, 100, 100);
                 canvas->save();
                 canvas->translate(0, SkIntToScalar(yPos));
-                canvas->clipRect(SkRect::MakeWH(110, 110), SkCanvas::kIntersect_Op, true);
+                canvas->clipRect(SkRect::MakeWH(110, 110), true);
                 canvas->drawPath(one, fOnePaint);
                 canvas->drawPath(one, fOutlinePaint);
                 canvas->drawPath(two, fTwoPaint);
@@ -87,7 +87,7 @@ protected:
                     Op(one, two, (SkPathOp) op, &result);
                     canvas->save();
                     canvas->translate(SkIntToScalar(xPos), SkIntToScalar(yPos));
-                    canvas->clipRect(SkRect::MakeWH(110, 110), SkCanvas::kIntersect_Op, true);
+                    canvas->clipRect(SkRect::MakeWH(110, 110), true);
                     canvas->drawPath(result, fOpPaint[op]);
                     canvas->drawPath(result, fOutlinePaint);
                     canvas->restore();