+ class UpdateContext {
+ public:
+ UpdateContext()
+ : m_compositingStackingContainer(0)
+ , m_compositingAncestor(0)
+ {
+ }
+
+ UpdateContext(const UpdateContext&, const RenderLayer&);
+
+ const RenderLayer* compositingContainer(const RenderLayer&) const;
+ private:
+ const RenderLayer* m_compositingStackingContainer;
+ const RenderLayer* m_compositingAncestor;
+ };
+