Reduce repetitive EventTarget subclassing

Source/core/events/EventTarget.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  *           (C) 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ skipping 113 matching lines @@
         bool hasCapturingEventListeners(const AtomicString& eventType);
         const EventListenerVector& getEventListeners(const AtomicString& eventType);
 
         bool fireEventListeners(Event*);
         bool isFiringEventListeners();
 
     protected:
         virtual ~EventTarget();
 
         virtual EventTargetData* eventTargetData() = 0;
-        virtual EventTargetData* ensureEventTargetData() = 0;
+        virtual EventTargetData& ensureEventTargetData() = 0;
 
     private:
         virtual void refEventTarget() = 0;
         virtual void derefEventTarget() = 0;
 
         DOMWindow* executingWindow();
         void fireEventListeners(Event*, EventTargetData*, EventListenerVector&);
         void countLegacyEvents(const AtomicString& legacyTypeName, EventListenerVector*, EventListenerVector*);
 
         bool clearAttributeEventListener(const AtomicString& eventType, DOMWrapperWorld* isolatedWorld);
 
         friend class EventListenerIterator;
     };
 
+    class EventTargetWithInlineData : public EventTarget {
+    protected:
+        virtual EventTargetData* eventTargetData() OVERRIDE FINAL { return &m_eventTargetData; }
+        virtual EventTargetData& ensureEventTargetData() OVERRIDE FINAL { return m_eventTargetData; }
+    private:
+        EventTargetData m_eventTargetData;
+    };
+
     // FIXME: These macros should be split into separate DEFINE and DECLARE
     // macros to avoid causing so many header includes.
     #define DEFINE_ATTRIBUTE_EVENT_LISTENER(attribute) \
         EventListener* on##attribute(DOMWrapperWorld* isolatedWorld) { return getAttributeEventListener(EventTypeNames::attribute, isolatedWorld); } \
         void setOn##attribute(PassRefPtr<EventListener> listener, DOMWrapperWorld* isolatedWorld = 0) { setAttributeEventListener(EventTypeNames::attribute, listener, isolatedWorld); } \
 
     #define DECLARE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(attribute) \
         virtual EventListener* on##attribute(DOMWrapperWorld* isolatedWorld); \
         virtual void setOn##attribute(PassRefPtr<EventListener>, DOMWrapperWorld* isolatedWorld); \
 
@@ skipping 45 matching lines @@
     {
         EventTargetData* d = eventTargetData();
         if (!d)
             return false;
         return d->eventListenerMap.containsCapturing(eventType);
     }
 
 } // namespace WebCore
 
 #endif // EventTarget_h