Fix bug where form/fieldset :valid/:invalid won't be recalculated upon control's willValidate change

Source/core/html/FormAssociatedElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 92 matching lines @@
     // FIXME: Remove usage of setForm. resetFormOwner should be enough, and
     // setForm is confusing.
     void setForm(HTMLFormElement*);
     void associateByParser(HTMLFormElement*);
     void formAttributeChanged();
 
     // If you add an override of willChangeForm() or didChangeForm() to a class
     // derived from this one, you will need to add a call to setForm(0) to the
     // destructor of that class.
     virtual void willChangeForm();
-    virtual void didChangeForm();
+    virtual void didChangeForm(HTMLFormElement* oldForm);
 
     String customValidationMessage() const;
 
 private:
 #if !ENABLE(OILPAN)
     virtual void refFormAssociatedElement() = 0;
     virtual void derefFormAssociatedElement() = 0;
 #endif
 
     void setFormAttributeTargetObserver(PassOwnPtrWillBeRawPtr<FormAttributeTargetObserver>);
@@ skipping 15 matching lines @@
 };
 
 HTMLElement* toHTMLElement(FormAssociatedElement*);
 HTMLElement& toHTMLElement(FormAssociatedElement&);
 const HTMLElement* toHTMLElement(const FormAssociatedElement*);
 const HTMLElement& toHTMLElement(const FormAssociatedElement&);
 
 } // namespace
 
 #endif // FormAssociatedElement_h