[Reland] Setup LayoutMenuList to not modify layout tree outside style recalc.

Source/core/layout/LayoutMenuList.h

 /*
  * This file is part of the select element layoutObject in WebCore.
  *
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 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 110 matching lines @@
     void setTextFromOption(int optionIndex);
     void updateOptionsWidth();
     void updateText();
     void setIndexToSelectOnCancel(int listIndex);
 
     void didUpdateActiveOption(int optionIndex);
 
     LayoutText* m_buttonText;
     LayoutBlock* m_innerBlock;
 
-    bool m_optionsChanged;
+    bool m_optionsChanged : 1;
+    bool m_isEmpty : 1;
+    bool m_hasUpdatedActiveOption : 1;
+    bool m_popupIsVisible : 1;
     int m_optionsWidth;
 
     int m_lastActiveIndex;
 
     RefPtr<ComputedStyle> m_optionStyle;
 
     RefPtrWillBePersistent<PopupMenu> m_popup;
-    bool m_popupIsVisible;
     int m_indexToSelectOnCancel;
 
     // TODO(tkent): Use FRIEND_TEST macro provided by gtest_prod.h
     friend class LayoutMenuListTest_ElementRectRelativeToViewport_Test;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutMenuList, isMenuList());
 
 }
 
 #endif