Introduce isHTMLLabelElement and toHTMLLabelElement

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 2774 matching lines @@
 {
     ASSERT(hasTagName(labelTag));
 
     if (!inDocument())
         return;
 
     if (oldForAttributeValue == newForAttributeValue)
         return;
 
     if (!oldForAttributeValue.isEmpty())
-        scope->removeLabel(oldForAttributeValue, static_cast<HTMLLabelElement*>(this));
+        scope->removeLabel(oldForAttributeValue, toHTMLLabelElement(this));
     if (!newForAttributeValue.isEmpty())
-        scope->addLabel(newForAttributeValue, static_cast<HTMLLabelElement*>(this));
+        scope->addLabel(newForAttributeValue, toHTMLLabelElement(this));
 }
 
 void Element::willModifyAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue)
 {
     if (isIdAttributeName(name))
         updateId(oldValue, newValue);
     else if (name == HTMLNames::nameAttr)
         updateName(oldValue, newValue);
     else if (name == HTMLNames::forAttr && hasTagName(labelTag)) {
         TreeScope* scope = treeScope();
@@ skipping 839 matching lines @@
     return 0;
 }
 
 Attribute* UniqueElementData::attributeItem(unsigned index)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(index < length());
     return &m_attributeVector.at(index);
 }
 
 } // namespace WebCore