Use new is*Element() helper functions further more in HTML code

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 56 matching lines @@
         result.setInnerNode(defaultArea);
         result.setURLElement(defaultArea);
     }
     return defaultArea;
 }
 
 HTMLImageElement* HTMLMapElement::imageElement()
 {
     RefPtr<HTMLCollection> images = document().images();
     for (unsigned i = 0; Element* curr = images->item(i); i++) {
-        if (!curr->hasTagName(imgTag))
-            continue;
+        ASSERT(isHTMLImageElement(curr));

[adamk, 2014/03/13 20:20:36]

I take it this is just asserting that Document::images() always returns image
elements...would be nice if we could represent that somehow in the C++ type even
if we can't in the DOM API. But that's for another time.

 
         // 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);
+        HTMLImageElement& imageElement = toHTMLImageElement(*curr);
+        String useMapName = imageElement.getAttribute(usemapAttr).string().substring(1);
         if (equalIgnoringCase(useMapName, m_name))
-            return imageElement;
+            return &imageElement;
     }
 
     return 0;
 }
 
 void HTMLMapElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     // FIXME: This logic seems wrong for XML documents.
     // Either the id or name will be used depending on the order the attributes are parsed.
 
@@ skipping 32 matching lines @@
 }
 
 void HTMLMapElement::removedFrom(ContainerNode* insertionPoint)
 {
     if (insertionPoint->inDocument())
         treeScope().removeImageMap(this);
     HTMLElement::removedFrom(insertionPoint);
 }
 
 }