Use new Traversal<HTML*Element> API more in accessibility

Source/core/accessibility/AXRenderObject.cpp

 /*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 2138 matching lines @@
 void AXRenderObject::addImageMapChildren()
 {
     RenderBoxModelObject* cssBox = renderBoxModelObject();
     if (!cssBox || !cssBox->isRenderImage())
         return;
 
     HTMLMapElement* map = toRenderImage(cssBox)->imageMap();
     if (!map)
         return;
 
-    for (Element* current = ElementTraversal::firstWithin(*map); current; current = ElementTraversal::next(*current, map)) {
+    for (HTMLAreaElement* area = Traversal<HTMLAreaElement>::firstWithin(*map); area; area = Traversal<HTMLAreaElement>::next(*area, map)) {
         // add an <area> element for this child if it has a link
-        if (isHTMLAreaElement(*current) && current->isLink()) {
+        if (area->isLink()) {
             AXImageMapLink* areaObject = toAXImageMapLink(axObjectCache()->getOrCreate(ImageMapLinkRole));
-            areaObject->setHTMLAreaElement(toHTMLAreaElement(current));
+            areaObject->setHTMLAreaElement(area);
             areaObject->setHTMLMapElement(map);
             areaObject->setParent(this);
             if (!areaObject->accessibilityIsIgnored())
                 m_children.append(areaObject);
             else
                 axObjectCache()->remove(areaObject->axObjectID());
         }
     }
 }
 
@@ skipping 145 matching lines @@
         if (label && label->renderer()) {
             LayoutRect labelRect = axObjectCache()->getOrCreate(label)->elementRect();
             result.unite(labelRect);
         }
     }
 
     return result;
 }
 
 } // namespace WebCore