Drop [TypeChecking=Nullable]; deduce from attribute type instead

Source/core/events/FocusEvent.h

 /*
  * Copyright (C) 2013 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 39 matching lines @@
     {
         return adoptRefWillBeNoop(new FocusEvent(type, canBubble, cancelable, view, detail, relatedTarget));
     }
 
     static PassRefPtrWillBeRawPtr<FocusEvent> create(const AtomicString& type, const FocusEventInit& initializer)
     {
         return adoptRefWillBeNoop(new FocusEvent(type, initializer));
     }
 
     EventTarget* relatedTarget() const { return m_relatedTarget.get(); }
-    EventTarget* relatedTarget(bool& isNull) const { isNull = !m_relatedTarget; return m_relatedTarget.get(); }
     void setRelatedTarget(EventTarget* relatedTarget) { m_relatedTarget = relatedTarget; }
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
     virtual bool isFocusEvent() const OVERRIDE;
 
     virtual void trace(Visitor*) OVERRIDE;
 
 private:
     FocusEvent();
     FocusEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<AbstractView>, int, EventTarget*);
@@ skipping 36 matching lines @@
     static PassRefPtrWillBeRawPtr<FocusOutEventDispatchMediator> create(PassRefPtrWillBeRawPtr<FocusEvent>);
 private:
     explicit FocusOutEventDispatchMediator(PassRefPtrWillBeRawPtr<FocusEvent>);
     FocusEvent* event() const { return static_cast<FocusEvent*>(EventDispatchMediator::event()); }
     virtual bool dispatchEvent(EventDispatcher*) const OVERRIDE;
 };
 
 } // namespace WebCore
 
 #endif // FocusEvent_h