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

gm/imagefilters.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkBlurImageFilter.h"
 #include "SkColorMatrixFilter.h"
@@ skipping 104 matching lines @@
 #include "SkRRect.h"
 
 static void draw_set(SkCanvas* canvas, sk_sp<SkImageFilter> filters[], int count) {
     const SkRect r = SkRect::MakeXYWH(30, 30, 200, 200);
     const SkScalar offset = 250;
     SkScalar dx = 0, dy = 0;
 
     for (int i = 0; i < count; ++i) {
         canvas->save();
         SkRRect rr = SkRRect::MakeRectXY(r.makeOffset(dx, dy), 20, 20);
-        canvas->clipRRect(rr, SkCanvas::kIntersect_Op, true);
+        canvas->clipRRect(rr, true);
         canvas->saveLayer({ &rr.getBounds(), nullptr, filters[i].get(), 0 });
         canvas->drawColor(0x40FFFFFF);
         canvas->restore();
         canvas->restore();
 
         if (0 == dx) {
             dx = offset;
         } else {
             dx = 0;
             dy = offset;
@@ skipping 32 matching lines @@
     canvas->translate(20, 20);
     for (const auto& xform : xforms) {
         canvas->save();
         canvas->translate(xform.fTx, xform.fTy);
         canvas->scale(xform.fSx, xform.fSy);
         canvas->drawImage(image, 0, 0, &paint);
         draw_set(canvas, filters, SK_ARRAY_COUNT(filters));
         canvas->restore();
     }
 }