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

Source/core/layout/LayoutImageResource.cpp

 /*
  * Copyright (C) 1999 Lars Knoll <knoll@kde.org>
  * Copyright (C) 1999 Antti Koivisto <koivisto@kde.org>
  * Copyright (C) 2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2006 Allan Sandfeld Jensen <kde@carewolf.com>
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  * Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2010 Patrick Gansterer <paroga@paroga.com>
  *
@@ skipping 15 matching lines @@
  */
 
 #include "config.h"
 #include "core/layout/LayoutImageResource.h"
 
 #include "core/layout/LayoutImage.h"
 
 namespace blink {
 
 LayoutImageResource::LayoutImageResource()
-    : m_layoutObject(0)
-    , m_cachedImage(0)
+    : m_layoutObject(nullptr)
+    , m_cachedImage(nullptr)
 {
 }
 
 LayoutImageResource::~LayoutImageResource()
 {
 }
 
 void LayoutImageResource::initialize(LayoutObject* layoutObject)
 {
     ASSERT(!m_layoutObject);
@@ skipping 51 matching lines @@
 {
     if (!m_cachedImage)
         return LayoutSize();
     LayoutSize size = m_cachedImage->imageSizeForLayoutObject(m_layoutObject, multiplier, type);
     if (m_layoutObject && m_layoutObject->isLayoutImage())
         size.scale(toLayoutImage(m_layoutObject)->imageDevicePixelRatio());
     return size;
 }
 
 } // namespace blink