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

gm/path_stroke_with_zero_length.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 "SkPath.h"
 #include "SkStream.h"
 #include "gm.h"
@@ skipping 149 matching lines @@
         SkMatrix clipM;
         clipM.reset();
         clipM.preScale(scale, scale);
         clipM.postTranslate(bounds.fLeft - 17, bounds.fTop - 24.5f + 420);
         SkPath clip;
         if (index < 2) {
             fClipL.transform(clipM, &clip);
         } else {
             fClipS.transform(clipM, &clip);
         }
-        canvas->clipPath(clip, SkCanvas::kIntersect_Op, true);
+        canvas->clipPath(clip, true);
         canvas->scale(scale, scale);
         canvas->drawBitmap(offscreen, (bounds.fLeft - 17) / scale,
                     (bounds.fTop - 20 + 420) / scale);
         canvas->restore();
 
         if (bounds.width() > 20) {
             canvas->save();
             clipM.reset();
             clipM.preScale(scale, scale);
             clipM.postTranslate(bounds.fLeft - 17 - 275, bounds.fTop - 24.5f + 420);
             SkPath clip;
             fClipR.transform(clipM, &clip);
-            canvas->clipPath(clip, SkCanvas::kIntersect_Op, true);
+            canvas->clipPath(clip, true);
             canvas->scale(10.f, 10.f);
             canvas->drawBitmap(offscreen, (bounds.fLeft - 17 - 275
                     + (index >= 5 ? 5 : 0)) / scale, (bounds.fTop - 20 + 420) / scale);
             canvas->restore();
         }
     }
 
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 DEF_GM( return new StrokeZeroGM(); )