Disabled select element should not fire onchange event.

Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * 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, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
@@ skipping 622 matching lines @@
     }
 
     scrollToSelection();
     setNeedsValidityCheck();
     notifyFormStateChanged();
 }
 
 void HTMLSelectElement::listBoxOnChange()
 {
     ASSERT(!usesMenuList() || m_multiple);
-    if (isDisabledFormControl())
-        return;
 
     const Vector<HTMLElement*>& items = listItems();
 
     // If the cached selection list is empty, or the size has changed, then fire
     // dispatchFormControlChangeEvent, and return early.
     if (m_lastOnChangeSelection.isEmpty() || m_lastOnChangeSelection.size() != items.size()) {
         dispatchFormControlChangeEvent();
         return;
     }
 
@@ skipping 915 matching lines @@
 }
 
 void HTMLSelectElement::finishParsingChildren()
 {
     HTMLFormControlElementWithState::finishParsingChildren();
     m_isParsingInProgress = false;
     updateListItemSelectedStates();
 }
 
 } // namespace