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

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

Index: third_party/WebKit/Source/platform/graphics/Path.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/Path.cpp b/third_party/WebKit/Source/platform/graphics/Path.cpp
index 963a955fe3f9a023ea0b45598e402a18c4b490d4..7f36cbccdd42c494e9d7ec90408c27fd2d996ee1 100644
--- a/third_party/WebKit/Source/platform/graphics/Path.cpp
+++ b/third_party/WebKit/Source/platform/graphics/Path.cpp
@@ -50,6 +50,11 @@ Path::Path(const Path& other)
     m_path = SkPath(other.m_path);
 }
 
+Path::Path(const SkPath& other)
+{
+    m_path = other;
+}
+
 Path::~Path()
 {
 }
@@ -508,6 +513,11 @@ bool Path::unionPath(const Path& other)
     return Op(m_path, other.m_path, kUnion_SkPathOp, &m_path);
 }
 
+bool Path::intersectPath(const Path& other)
+{
+    return Op(m_path, other.m_path, kIntersect_SkPathOp, &m_path);
+}
+
 #if ENABLE(ASSERT)
 bool ellipseIsRenderable(float startAngle, float endAngle)
 {