Implement contextmenu attribute with basic support of <menu>

Source/core/html/HTMLMenuitemElement.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
-#include "core/html/HTMLPictureElement.h"
+#include "core/html/HTMLMenuitemElement.h"
 
 #include "HTMLNames.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
-HTMLPictureElement::HTMLPictureElement(Document& document)
-    : HTMLElement(pictureTag, document)
+inline HTMLMenuitemElement::HTMLMenuitemElement(Document& document)
+    : HTMLElement(menuitemTag, document)
 {
     ScriptWrappable::init(this);
 }
 
-PassRefPtr<HTMLPictureElement> HTMLPictureElement::create(Document& document)
+PassRefPtr<HTMLMenuitemElement> HTMLMenuitemElement::create(Document& document)
 {
-    return adoptRef(new HTMLPictureElement(document));
+    return adoptRef(new HTMLMenuitemElement(document));
 }
 
-} // namespace
+}