Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/editing/InsertListCommand.cpp

 /*
  * Copyright (C) 2006, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 47 matching lines @@
 }
 
 PassRefPtr<HTMLElement> InsertListCommand::mergeWithNeighboringLists(PassRefPtr<HTMLElement> passedList)
 {
     RefPtr<HTMLElement> list = passedList;
     Element* previousList = ElementTraversal::previousSibling(*list);
     if (canMergeLists(previousList, list.get()))
         mergeIdenticalElements(previousList, list);
 
     if (!list)
-        return 0;
+        return nullptr;
 
     Element* nextSibling = ElementTraversal::nextSibling(*list);
     if (!nextSibling || !nextSibling->isHTMLElement())
         return list.release();
 
     RefPtr<HTMLElement> nextList = toHTMLElement(nextSibling);
     if (canMergeLists(list.get(), nextList.get())) {
         mergeIdenticalElements(list, nextList);
         return nextList.release();
     }
@@ skipping 247 matching lines @@
 
     return listNode;
 }
 
 PassRefPtr<HTMLElement> InsertListCommand::listifyParagraph(const VisiblePosition& originalStart, const QualifiedName& listTag)
 {
     VisiblePosition start = startOfParagraph(originalStart, CanSkipOverEditingBoundary);
     VisiblePosition end = endOfParagraph(start, CanSkipOverEditingBoundary);
 
     if (start.isNull() || end.isNull())
-        return 0;
+        return nullptr;
 
     // Check for adjoining lists.
     RefPtr<HTMLElement> listItemElement = createListItemElement(document());
     RefPtr<HTMLElement> placeholder = createBreakElement(document());
     appendNode(placeholder, listItemElement);
 
     // Place list item into adjoining lists.
     Element* previousList = adjacentEnclosingList(start.deepEquivalent(), start.previous(CannotCrossEditingBoundary), listTag);
     Element* nextList = adjacentEnclosingList(start.deepEquivalent(), end.next(CannotCrossEditingBoundary), listTag);
     RefPtr<HTMLElement> listElement;
@@ skipping 44 matching lines @@
     if (listElement)
         return mergeWithNeighboringLists(listElement);
 
     if (canMergeLists(previousList, nextList))
         mergeIdenticalElements(previousList, nextList);
 
     return listElement;
 }
 
 }