Make classes and structures in core/dom fast-allocated.

Source/core/dom/ElementFullscreen.h

 // 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.
 
 #ifndef ElementFullscreen_h
 #define ElementFullscreen_h
 
 #include "core/events/EventTarget.h"
+#include "wtf/Allocator.h"
 
 namespace blink {
 
 class Element;
 
 class ElementFullscreen {
+    STATIC_ONLY(ElementFullscreen);
 public:
     static void requestFullscreen(Element&);
 
     static void webkitRequestFullscreen(Element&);
 
     DEFINE_STATIC_ATTRIBUTE_EVENT_LISTENER(webkitfullscreenchange);
     DEFINE_STATIC_ATTRIBUTE_EVENT_LISTENER(webkitfullscreenerror);
 };
 
 } // namespace blink
 
 #endif // ElementFullscreen_h