Use new Traversal<HTML*Element> API in HTML code

Source/core/html/HTMLFieldSetElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * 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 49 matching lines @@
 void HTMLFieldSetElement::disabledAttributeChanged()
 {
     // This element must be updated before the style of nodes in its subtree gets recalculated.
     HTMLFormControlElement::disabledAttributeChanged();
     invalidateDisabledStateUnder(*this);
 }
 
 void HTMLFieldSetElement::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
 {
     HTMLFormControlElement::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
-    for (Element* element = ElementTraversal::firstWithin(*this); element; element = ElementTraversal::nextSkippingChildren(*element, this)) {
-        if (element->hasTagName(legendTag))
-            invalidateDisabledStateUnder(*element);
-    }
+    for (HTMLLegendElement* legend = Traversal<HTMLLegendElement>::firstChild(*this); legend; legend = Traversal<HTMLLegendElement>::nextSibling(*legend))
+        invalidateDisabledStateUnder(*legend);
 }
 
 bool HTMLFieldSetElement::supportsFocus() const
 {
     return HTMLElement::supportsFocus();
 }
 
 const AtomicString& HTMLFieldSetElement::formControlType() const
 {
     DEFINE_STATIC_LOCAL(const AtomicString, fieldset, ("fieldset", AtomicString::ConstructFromLiteral));
     return fieldset;
 }
 
 RenderObject* HTMLFieldSetElement::createRenderer(RenderStyle*)
 {
     return new RenderFieldset(this);
 }
 
 HTMLLegendElement* HTMLFieldSetElement::legend() const
 {
-    for (Element* child = ElementTraversal::firstWithin(*this); child; child = ElementTraversal::nextSkippingChildren(*child, this)) {
-        if (child->hasTagName(legendTag))
-            return toHTMLLegendElement(child);
-    }
-    return 0;
+    return Traversal<HTMLLegendElement>::firstChild(*this);
 }
 
 PassRefPtr<HTMLCollection> HTMLFieldSetElement::elements()
 {
     return ensureCachedHTMLCollection(FormControls);
 }
 
 void HTMLFieldSetElement::refreshElementsIfNeeded() const
 {
     uint64_t docVersion = document().domTreeVersion();
@@ skipping 17 matching lines @@
     }
 }
 
 const Vector<FormAssociatedElement*>& HTMLFieldSetElement::associatedElements() const
 {
     refreshElementsIfNeeded();
     return m_associatedElements;
 }
 
 } // namespace