C++11: Replace 0 with nullptr where applicable in layout code.

Source/core/layout/line/LineLayoutState.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2014 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 16 matching lines @@
 #include "core/layout/LayoutBlockFlow.h"
 #include "platform/geometry/LayoutRect.h"
 
 namespace blink {
 
 // Like LayoutState for layout(), LineLayoutState keeps track of global information
 // during an entire linebox tree layout pass (aka layoutInlineChildren).
 class LineLayoutState {
 public:
     LineLayoutState(bool fullLayout, LayoutUnit& paintInvalidationLogicalTop, LayoutUnit& paintInvalidationLogicalBottom, LayoutFlowThread* flowThread)
-        : m_lastFloat(0)
-        , m_endLine(0)
+        : m_lastFloat(nullptr)
+        , m_endLine(nullptr)
         , m_floatIndex(0)
         , m_endLineLogicalTop(0)
         , m_endLineMatched(false)
         , m_hasInlineChild(false)
         , m_isFullLayout(fullLayout)
         , m_containsBRWithClear(false)
         , m_paintInvalidationLogicalTop(paintInvalidationLogicalTop)
         , m_paintInvalidationLogicalBottom(paintInvalidationLogicalBottom)
         , m_adjustedLogicalLineTop(0)
         , m_usesPaintInvalidationBounds(false)
@@ skipping 72 matching lines @@
     LayoutUnit m_adjustedLogicalLineTop;
 
     bool m_usesPaintInvalidationBounds;
 
     LayoutFlowThread* m_flowThread;
 };
 
 }
 
 #endif // LineLayoutState_h