Canvas2d: Make the intersection computation O(1) instead of O(n) in ClipList.

third_party/WebKit/Source/platform/graphics/Path.h

 /*
  * Copyright (C) 2003, 2006, 2009 Apple Inc. All rights reserved.
  *               2006 Rob Buis <buis@kde.org>
  * Copyright (C) 2007-2008 Torch Mobile, Inc.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 52 matching lines @@
 
 typedef void (*PathApplierFunction)(void* info, const PathElement*);
 
 class PLATFORM_EXPORT Path {
     USING_FAST_MALLOC(Path);
 public:
     Path();
     ~Path();
 
     Path(const Path&);
+    Path(const SkPath&);
     Path& operator=(const Path&);
     Path& operator=(const SkPath&);
     bool operator==(const Path&) const;
 
     bool contains(const FloatPoint&) const;
     bool contains(const FloatPoint&, WindRule) const;
     bool strokeContains(const FloatPoint&, const StrokeData&) const;
     FloatRect boundingRect() const;
     FloatRect strokeBoundingRect(const StrokeData&) const;
 
@@ skipping 60 matching lines @@
 
     void apply(void* info, PathApplierFunction) const;
     void transform(const AffineTransform&);
 
     void addPathForRoundedRect(const FloatRect&, const FloatSize& topLeftRadius, const FloatSize& topRightRadius, const FloatSize& bottomLeftRadius, const FloatSize& bottomRightRadius);
 
     bool subtractPath(const Path&);
 
     // Updates the path to the union (inclusive-or) of itself with the given argument.
     bool unionPath(const Path& other);
+    bool intersectPath(const Path& other);
 
 private:
     void addEllipse(const FloatPoint&, float radiusX, float radiusY, float startAngle, float endAngle, bool anticlockwise);
     SkPath strokePath(const StrokeData&) const;
 
     SkPath m_path;
 };
 
 #if ENABLE(ASSERT)
 PLATFORM_EXPORT bool ellipseIsRenderable(float startAngle, float endAngle);
 #endif
 
 } // namespace blink
 
 #endif