Have HTMLCollection::item() return an Element as per specification

Source/core/html/HTMLMapElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@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 58 matching lines @@
     if (defaultArea) {
         result.setInnerNode(defaultArea);
         result.setURLElement(defaultArea);
     }
     return defaultArea;
 }
 
 HTMLImageElement* HTMLMapElement::imageElement()
 {
     RefPtr<HTMLCollection> images = document().images();
-    for (unsigned i = 0; Node* curr = images->item(i); i++) {
+    for (unsigned i = 0; Element* curr = images->item(i); i++) {
         if (!curr->hasTagName(imgTag))
             continue;
 
         // The HTMLImageElement's useMap() value includes the '#' symbol at the beginning,
         // which has to be stripped off.
         HTMLImageElement* imageElement = toHTMLImageElement(curr);
         String useMapName = imageElement->getAttribute(usemapAttr).string().substring(1);
         if (equalIgnoringCase(useMapName, m_name))
             return imageElement;
     }
@@ skipping 41 matching lines @@
 }
 
 void HTMLMapElement::removedFrom(ContainerNode* insertionPoint)
 {
     if (insertionPoint->inDocument())
         treeScope().removeImageMap(this);
     HTMLElement::removedFrom(insertionPoint);
 }
 
 }