Deprecate the Element.prefix setter

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 1183 matching lines @@
     return true;
 }
 
 String Element::nodeName() const
 {
     return m_tagName.toString();
 }
 
 void Element::setPrefix(const AtomicString& prefix, ExceptionState& exceptionState)
 {
-    UseCounter::count(document(), UseCounter::ElementSetPrefix);
+    UseCounter::countDeprecation(document(), UseCounter::ElementSetPrefix);
 
     if (!prefix.isEmpty() && !Document::isValidName(prefix)) {
         exceptionState.throwDOMException(InvalidCharacterError, "The prefix '" + prefix + "' is not a valid name.");
         return;
     }
 
     // FIXME: Raise NamespaceError if prefix is malformed per the Namespaces in XML specification.
 
     const AtomicString& nodeNamespaceURI = namespaceURI();
     if (nodeNamespaceURI.isEmpty() && !prefix.isEmpty()) {
@@ skipping 2086 matching lines @@
 
 void Element::trace(Visitor* visitor)
 {
     if (hasRareData())
         visitor->trace(elementRareData());
 
     ContainerNode::trace(visitor);
 }
 
 } // namespace WebCore