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

Source/web/WebDocument.cpp

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 146 matching lines @@
     return WebNodeCollection(unwrap<Document>()->all());
 }
 
 void WebDocument::images(WebVector<WebElement>& results)
 {
     RefPtr<HTMLCollection> images = unwrap<Document>()->images();
     size_t sourceLength = images->length();
     Vector<WebElement> temp;
     temp.reserveCapacity(sourceLength);
     for (size_t i = 0; i < sourceLength; ++i) {
-        Node* node = images->item(i);
-        if (node && node->isHTMLElement())
-            temp.append(WebElement(toElement(node)));
+        Element* element = images->item(i);
+        if (element && element->isHTMLElement())
+            temp.append(WebElement(element));
     }
     results.assign(temp);
 }
 
 void WebDocument::forms(WebVector<WebFormElement>& results) const
 {
     RefPtr<HTMLCollection> forms = const_cast<Document*>(constUnwrap<Document>())->forms();
     size_t sourceLength = forms->length();
     Vector<WebFormElement> temp;
     temp.reserveCapacity(sourceLength);
     for (size_t i = 0; i < sourceLength; ++i) {
-        Node* node = forms->item(i);
+        Element* element = forms->item(i);
         // Strange but true, sometimes node can be 0.
-        if (node && node->isHTMLElement())
-            temp.append(WebFormElement(toHTMLFormElement(node)));
+        if (element && element->isHTMLElement())
+            temp.append(WebFormElement(toHTMLFormElement(element)));
     }
     results.assign(temp);
 }
 
 WebURL WebDocument::completeURL(const WebString& partialURL) const
 {
     return constUnwrap<Document>()->completeURL(partialURL);
 }
 
 WebElement WebDocument::getElementById(const WebString& id) const
@@ skipping 120 matching lines @@
     m_private = elem;
     return *this;
 }
 
 WebDocument::operator PassRefPtr<Document>() const
 {
     return toDocument(m_private.get());
 }
 
 } // namespace blink