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

Source/core/layout/LayoutCounter.cpp

 /**
  * Copyright (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 286 matching lines @@
     if (object.hasCounterNodeMap()) {
         if (CounterMap* nodeMap = counterMaps().get(&object)) {
             if (CounterNode* node = nodeMap->get(identifier))
                 return node;
         }
     }
 
     bool isReset = false;
     int value = 0;
     if (!planCounter(object, identifier, isReset, value) && !alwaysCreateCounter)
-        return 0;
+        return nullptr;
 
     RefPtr<CounterNode> newParent = nullptr;
     RefPtr<CounterNode> newPreviousSibling = nullptr;
     RefPtr<CounterNode> newNode = CounterNode::create(object, isReset, value);
     if (findPlaceForCounter(object, identifier, isReset, newParent, newPreviousSibling))
         newParent->insertAfter(newNode.get(), newPreviousSibling.get(), identifier);
     CounterMap* nodeMap;
     if (object.hasCounterNodeMap()) {
         nodeMap = counterMaps().get(&object);
     } else {
@@ skipping 22 matching lines @@
         if (stayWithin == parentElement(*currentLayoutObject) && currentCounter->hasResetType())
             break;
         newNode->insertAfter(currentCounter, newNode->lastChild(), identifier);
     }
     return newNode.get();
 }
 
 LayoutCounter::LayoutCounter(Document* node, const CounterContent& counter)
     : LayoutText(node, StringImpl::empty())
     , m_counter(counter)
-    , m_counterNode(0)
-    , m_nextForSameCounter(0)
+    , m_counterNode(nullptr)
+    , m_nextForSameCounter(nullptr)
 {
     view()->addLayoutCounter();
 }
 
 LayoutCounter::~LayoutCounter()
 {
 }
 
 void LayoutCounter::willBeDestroyed()
 {
@@ skipping 236 matching lines @@
             fprintf(stderr, "    ");
         fprintf(stderr, "%p N:%p P:%p PS:%p NS:%p C:%p\n",
             current, current->node(), current->parent(), current->previousSibling(),
             current->nextSibling(), current->hasCounterNodeMap() ?
             counterName ? blink::counterMaps().get(current)->get(identifier) : (blink::CounterNode*)1 : (blink::CounterNode*)0);
     }
     fflush(stderr);
 }
 
 #endif // NDEBUG