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

Source/web/WebPageSerializer.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 147 matching lines @@
         return;
 
     // If we have already seen that frame, ignore it.
     if (visitedFrames->contains(frame))
         return;
     visitedFrames->append(frame);
     if (!frameURLs->contains(frameURL))
         frameURLs->append(frameURL);
 
     // Now get the resources associated with each node of the document.
-    RefPtr<HTMLCollection> allNodes = frame->document()->all();
-    for (unsigned i = 0; i < allNodes->length(); ++i) {
-        Node* node = allNodes->item(i);
-        // We are only interested in HTML resources.
-        if (!node->isElementNode())
-            continue;
-        retrieveResourcesForElement(toElement(node),
+    RefPtr<HTMLCollection> allElements = frame->document()->all();
+    for (unsigned i = 0; i < allElements->length(); ++i) {
+        Element* element = allElements->item(i);
+        retrieveResourcesForElement(element,
                                     visitedFrames, framesToVisit,
                                     frameURLs, resourceURLs);
     }
 }
 
 } // namespace
 
 namespace blink {
 
 void WebPageSerializer::serialize(WebView* view, WebVector<WebPageSerializer::Resource>* resourcesParam)
@@ skipping 107 matching lines @@
 
 WebString WebPageSerializer::generateBaseTagDeclaration(const WebString& baseTarget)
 {
     if (baseTarget.isEmpty())
         return String("<base href=\".\">");
     String baseString = "<base href=\".\" target=\"" + static_cast<const String&>(baseTarget) + "\">";
     return baseString;
 }
 
 } // namespace blink