IDL: make optional arguments (without default) explicit sometimes

Source/core/dom/DOMTokenList.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
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  * modification, are permitted provided that the following conditions
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  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 #ifndef DOMTokenList_h
 #define DOMTokenList_h
 
+#include "bindings/core/v8/Optional.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class Element;
 class ExceptionState;
 
@@ skipping 13 matching lines @@
 #endif
 
     virtual unsigned length() const = 0;
     virtual const AtomicString item(unsigned index) const = 0;
 
     bool contains(const AtomicString&, ExceptionState&) const;
     virtual void add(const Vector<String>&, ExceptionState&);
     void add(const AtomicString&, ExceptionState&);
     virtual void remove(const Vector<String>&, ExceptionState&);
     void remove(const AtomicString&, ExceptionState&);
-    bool toggle(const AtomicString&, ExceptionState&);
-    bool toggle(const AtomicString&, bool force, ExceptionState&);
+    bool toggle(const AtomicString&, Optional<bool> force, ExceptionState&);
 
     const AtomicString& toString() const { return value(); }
 
     virtual Element* element() { return 0; }
 
     virtual void trace(Visitor*) { }
 
 protected:
     virtual const AtomicString& value() const = 0;
     virtual void setValue(const AtomicString&) = 0;
 
     virtual void addInternal(const AtomicString&);
     virtual bool containsInternal(const AtomicString&) const = 0;
     virtual void removeInternal(const AtomicString&);
 
     static bool validateToken(const String&, ExceptionState&);
     static bool validateTokens(const Vector<String>&, ExceptionState&);
     static AtomicString addToken(const AtomicString&, const AtomicString&);
     static AtomicString addTokens(const AtomicString&, const Vector<String>&);
     static AtomicString removeToken(const AtomicString&, const AtomicString&);
     static AtomicString removeTokens(const AtomicString&, const Vector<String>&);
 };
 
 } // namespace blink
 
 #endif // DOMTokenList_h