enable conservative raster clipping

include/core/SkCanvas.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 1418 matching lines @@
     bool wouldOverwriteEntireSurface(const SkRect*, const SkPaint*, ShaderOverrideOpacity) const;
 
 
     /*  These maintain a cache of the clip bounds in local coordinates,
         (converted to 2s-compliment if floats are slow).
      */
     mutable SkRect fCachedLocalClipBounds;
     mutable bool   fCachedLocalClipBoundsDirty;
     bool fAllowSoftClip;
     bool fAllowSimplifyClip;
-    bool fConservativeRasterClip;
+    const bool fConservativeRasterClip;
 
     const SkRect& getLocalClipBounds() const {
         if (fCachedLocalClipBoundsDirty) {
             if (!this->getClipBounds(&fCachedLocalClipBounds)) {
                 fCachedLocalClipBounds.setEmpty();
             }
             fCachedLocalClipBoundsDirty = false;
         }
         return fCachedLocalClipBounds;
     }
@@ skipping 111 matching lines @@
 
 class SkCanvasClipVisitor {
 public:
     virtual ~SkCanvasClipVisitor();
     virtual void clipRect(const SkRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipRRect(const SkRRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) = 0;
 };
 
 #endif