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

gm/samplerstress.cpp

 /*
  * Copyright 2012 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 "SkBlurMaskFilter.h"
 #include "SkCanvas.h"
@@ skipping 90 matching lines @@
 
         SkRect temp;
         temp.set(SkIntToScalar(115),
                  SkIntToScalar(75),
                  SkIntToScalar(144),
                  SkIntToScalar(110));
 
         SkPath path;
         path.addRoundRect(temp, SkIntToScalar(5), SkIntToScalar(5));
 
-        canvas->clipPath(path, SkCanvas::kReplace_Op, true); // AA is on
+        canvas->clipPath(path, true); // AA is on
 
         canvas->drawText("M", 1,
                          SkIntToScalar(100), SkIntToScalar(100),
                          paint);
 
         canvas->restore();
 
         // Now draw stroked versions of the "M" and the round rect so we can
         // see what is going on
         SkPaint paint2;
@@ skipping 20 matching lines @@
 
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new SamplerStressGM; }
 static GMRegistry reg(MyFactory);
 
 }