Pass a struct to ContainerNode::childrenChanged() instead of separate arguments

Source/core/html/HTMLOptGroupElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2010 Apple 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 32 matching lines @@
 
 private:
     explicit HTMLOptGroupElement(Document&);
 
     virtual bool rendererIsFocusable() const OVERRIDE;
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual bool rendererIsNeeded(const RenderStyle&) OVERRIDE { return false; }
     virtual void attach(const AttachContext& = AttachContext()) OVERRIDE;
     virtual void detach(const AttachContext& = AttachContext()) OVERRIDE;
 
-    virtual void childrenChanged(bool changedByParser = false, Node* beforeChange = 0, Node* afterChange = 0, int childCountDelta = 0) OVERRIDE;
+    virtual void childrenChanged(const ChildrenChange&) OVERRIDE;
 
     virtual void accessKeyAction(bool sendMouseEvents) OVERRIDE;
 
     // <optgroup> never has a renderer so we manually manage a cached style.
     void updateNonRenderStyle();
     virtual RenderStyle* nonRendererStyle() const OVERRIDE;
     virtual PassRefPtr<RenderStyle> customStyleForRenderer() OVERRIDE;
 
     void recalcSelectOptions();
 
     RefPtr<RenderStyle> m_style;
 };
 
 } //namespace
 
 #endif