Introduce few const getters for dom classes

third_party/WebKit/Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 186 matching lines @@
     }
 #endif
 }
 
 inline ElementRareData* Element::elementRareData() const
 {
     DCHECK(hasRareData());
     return static_cast<ElementRareData*>(rareData());
 }
 
+ElementRareData* Element::maybeElementRareData() const
+{
+    return hasRareData() ? static_cast<ElementRareData*>(rareData()) : nullptr;
+}
+
 inline ElementRareData& Element::ensureElementRareData()
 {
     return static_cast<ElementRareData&>(ensureRareData());
 }
 
 bool Element::hasElementFlagInternal(ElementFlags mask) const
 {
     return elementRareData()->hasElementFlag(mask);
 }
 
@@ skipping 3455 matching lines @@
 
 DEFINE_TRACE(Element)
 {
     if (hasRareData())
         visitor->trace(elementRareData());
     visitor->trace(m_elementData);
     ContainerNode::trace(visitor);
 }
 
 } // namespace blink