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

Source/core/layout/LayoutListMarker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  * Copyright (C) 2010 Daniel Bates (dbates@intudata.com)
  *
  * 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
@@ skipping 1031 matching lines @@
         return toGeorgian(value);
     case Hebrew:
         return toHebrew(value);
     }
 
     ASSERT_NOT_REACHED();
     return "";
 }
 
 LayoutListMarker::LayoutListMarker(LayoutListItem* item)
-    : LayoutBox(0)
+    : LayoutBox(nullptr)
     , m_listItem(item)
 {
     // init LayoutObject attributes
     setInline(true); // our object is Inline
     setReplaced(true); // pretend to be replaced
 }
 
 LayoutListMarker::~LayoutListMarker()
 {
 }
@@ skipping 580 matching lines @@
     if (style()) {
         // Reuse the current margins. Otherwise resetting the margins to initial values
         // would trigger unnecessary layout.
         newStyle->setMarginStart(style()->marginStart());
         newStyle->setMarginEnd(style()->marginRight());
     }
     setStyle(newStyle.release());
 }
 
 } // namespace blink