Add UseCounters for access to and change of Attr's child Text nodes

Source/core/dom/Attr.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2012 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
@@ skipping 150 matching lines @@
 bool Attr::childTypeAllowed(NodeType type) const
 {
     return TEXT_NODE == type;
 }
 
 void Attr::childrenChanged(const ChildrenChange&)
 {
     if (m_ignoreChildrenChanged > 0)
         return;
 
+    UseCounter::count(document(), UseCounter::AttrChildChange);
+
     QualifiedName name = qualifiedName();
     invalidateNodeListCachesInAncestors(&name, m_element);
 
     StringBuilder valueBuilder;
     for (Node *n = firstChild(); n; n = n->nextSibling()) {
         if (n->isTextNode())
             valueBuilder.append(toText(n)->data());
     }
 
     AtomicString newValue = valueBuilder.toAtomicString();
@@ skipping 37 matching lines @@
     m_standaloneValueOrAttachedLocalName = attachedLocalName;
 }
 
 void Attr::trace(Visitor* visitor)
 {
     visitor->trace(m_element);
     ContainerNode::trace(visitor);
 }
 
 }