Make LayoutState always be RAII

Source/core/rendering/RenderBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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
@@ skipping 296 matching lines @@
         clearNeedsLayout();
         return;
     }
 
     LayoutStateMaintainer statePusher(*this, locationOffset());
     while (child) {
         child->layoutIfNeeded();
         ASSERT(!child->needsLayout());
         child = child->nextSibling();
     }
-
-    m_overflow.clear();
-    addVisualEffectOverflow();
-
-    statePusher.pop();
     invalidateBackgroundObscurationStatus();
     clearNeedsLayout();
 }
 
 // More IE extensions.  clientWidth and clientHeight represent the interior of an object
 // excluding border and scrollbar.
 LayoutUnit RenderBox::clientWidth() const
 {
     return width() - borderLeft() - borderRight() - verticalScrollbarWidth();
 }
@@ skipping 4350 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore