Intersection Observer first draft

Source/core/layout/LayoutObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 1040 matching lines @@
     // to invalidate its descendants which are painted on the same backing. However, for
     // an object (e.g. LayoutScrollbarPart, custom scroll corner, custom resizer) which is
     // not hooked up in the layout tree and not able to find its paint backing, it should
     // let its owning layout object call the following function.
     // FIXME: should we hook up scrollbar parts in the layout tree? crbug.com/484263.
     void invalidateDisplayItemClientForNonCompositingDescendantsOf(const LayoutObject&) const;
 
     // Called before anonymousChild.setStyle(). Override to set custom styles for the child.
     virtual void updateAnonymousChildStyle(const LayoutObject& anonymousChild, ComputedStyle& style) const { }
 
+    bool hasIntersectionObserver() { return  m_node && m_node->hasIntersectionObserver(); }
+
 protected:
     enum LayoutObjectType {
         LayoutObjectBr,
         LayoutObjectCanvas,
         LayoutObjectFieldset,
         LayoutObjectCounter,
         LayoutObjectDetailsMarker,
         LayoutObjectEmbeddedObject,
         LayoutObjectFileUploadControl,
         LayoutObjectFrame,
@@ skipping 598 matching lines @@
 void showTree(const blink::LayoutObject*);
 void showLineTree(const blink::LayoutObject*);
 void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 void showLayoutTree(const blink::LayoutObject* object1, const blink::LayoutObject* object2);
 
 #endif
 
 #endif // LayoutObject_h