Use C++11 features in core/html

Source/core/html/HTMLTableCellElement.cpp

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2010 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
@@ skipping 103 matching lines @@
         if (renderer() && renderer()->isTableCell())
             toRenderTableCell(renderer())->colSpanOrRowSpanChanged();
     } else
         HTMLTablePartElement::parseAttribute(name, value);
 }
 
 const StylePropertySet* HTMLTableCellElement::additionalPresentationAttributeStyle()
 {
     if (HTMLTableElement* table = findParentTable())
         return table->additionalCellStyle();
-    return 0;
+    return nullptr;
 }
 
 bool HTMLTableCellElement::isURLAttribute(const Attribute& attribute) const
 {
     return attribute.name() == backgroundAttr || HTMLTablePartElement::isURLAttribute(attribute);
 }
 
 bool HTMLTableCellElement::hasLegalLinkAttribute(const QualifiedName& name) const
 {
     return (hasTagName(tdTag) && name == backgroundAttr) || HTMLTablePartElement::hasLegalLinkAttribute(name);
@@ skipping 31 matching lines @@
 
 const AtomicString& HTMLTableCellElement::scope() const
 {
     return fastGetAttribute(scopeAttr);
 }
 
 HTMLTableCellElement* HTMLTableCellElement::cellAbove() const
 {
     RenderObject* cellRenderer = renderer();
     if (!cellRenderer)
-        return 0;
+        return nullptr;
     if (!cellRenderer->isTableCell())
-        return 0;
+        return nullptr;
 
     RenderTableCell* tableCellRenderer = toRenderTableCell(cellRenderer);
     RenderTableCell* cellAboveRenderer = tableCellRenderer->table()->cellAbove(tableCellRenderer);
     if (!cellAboveRenderer)
-        return 0;
+        return nullptr;
 
     return toHTMLTableCellElement(cellAboveRenderer->node());
 }
 
 } // namespace blink