Improve performance of HTMLSelectElement::deselectItemsWithoutValidation().

third_party/WebKit/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 1174 matching lines @@
     // change events for list boxes whenever the selection change is actually
     // made.  This matches other browsers' behavior.
     if (usesMenuList())
         dispatchInputAndChangeEventForMenuList();
     m_lastOnChangeSelection.clear();
     HTMLFormControlElementWithState::dispatchBlurEvent(newFocusedElement, type, sourceCapabilities);
 }
 
 void HTMLSelectElement::deselectItemsWithoutValidation(HTMLElement* excludeElement)
 {
+    if (!multiple() && usesMenuList() && m_lastOnChangeOption && m_lastOnChangeOption != excludeElement) {
+        m_lastOnChangeOption->setSelectedState(false);
+        return;
+    }
     for (auto& element : listItems()) {
         if (element != excludeElement && isHTMLOptionElement(*element))
             toHTMLOptionElement(element)->setSelectedState(false);
     }
 }
 
 FormControlState HTMLSelectElement::saveFormControlState() const
 {
     const ListItems& items = listItems();
     size_t length = items.size();
@@ skipping 931 matching lines @@
 }
 
 void HTMLSelectElement::didMutateSubtree()
 {
     DCHECK(popupIsVisible());
     DCHECK(m_popup);
     m_popup->updateFromElement(PopupMenu::ByDOMChange);
 }
 
 } // namespace blink