REGRESSION: Select listbox dispatches a change event on scroll.

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 1320 matching lines @@
                     updateListBoxSelection(false);
                 } else {
                     setActiveSelectionAnchorIndex(listIndex);
                     setActiveSelectionEndIndex(listIndex);
                     updateListBoxSelection(true);
                 }
             }
             event->setDefaultHandled();
         }
     } else if (event->type() == eventNames().mouseupEvent && event->isMouseEvent() && static_cast<MouseEvent*>(event)->button() == LeftButton && document()->frame()->eventHandler()->autoscrollRenderer() != renderer()) {
+        // We didn't start this click/drag on any options.
+        if (m_lastOnChangeSelection.isEmpty())
+            return;
         // This makes sure we fire dispatchFormControlChangeEvent for a single
         // click. For drag selection, onChange will fire when the autoscroll
         // timer stops.
         listBoxOnChange();
     } else if (event->type() == eventNames().keydownEvent) {
         if (!event->isKeyboardEvent())
             return;
         const String& keyIdentifier = static_cast<KeyboardEvent*>(event)->keyIdentifier();
 
         bool handled = false;
@@ skipping 213 matching lines @@
 }
 
 void HTMLSelectElement::finishParsingChildren()
 {
     HTMLFormControlElementWithState::finishParsingChildren();
     m_isParsingInProgress = false;
     updateListItemSelectedStates();
 }
 
 } // namespace