Clear the suggested value while setting value for <select> element.

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 240 matching lines @@
                 if (toHTMLOptionElement(items[i])->value() == value)
                     break;
                 optionIndex++;
             }
         }
         if (optionIndex >= static_cast<int>(items.size()))
             optionIndex = -1;
     }
 
     int previousSelectedIndex = selectedIndex();
+    setSuggestedIndex(-1);
     setSelectedIndex(optionIndex);
 
     if (sendEvents && previousSelectedIndex != selectedIndex()) {
         if (usesMenuList())
             dispatchInputAndChangeEventForMenuList(false);
         else
             listBoxOnChange();
     }
 }
 
@@ skipping 1387 matching lines @@
 
 void HTMLSelectElement::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_listItems);
 #endif
     HTMLFormControlElementWithState::trace(visitor);
 }
 
 } // namespace