Remove Node.prefix so it's no longer visible to script.

Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 499 matching lines @@
             node = NodeTraversal::nextPostOrder(*node);
     }
 }
 
 const AtomicString& Node::prefix() const
 {
     // For nodes other than elements and attributes, the prefix is always null
     return nullAtom;
 }
 
-void Node::setPrefix(const AtomicString& /*prefix*/, ExceptionState& exceptionState)
-{
-    // The spec says that for nodes other than elements and attributes, prefix is always null.
-    // It does not say what to do when the user tries to set the prefix on another type of
-    // node, however Mozilla throws a NamespaceError exception.
-    exceptionState.throwDOMException(NamespaceError, "Prefixes are only supported on element and attribute nodes.");
-}
-
 const AtomicString& Node::localName() const
 {
     return nullAtom;
 }
 
 const AtomicString& Node::namespaceURI() const
 {
     return nullAtom;
 }
 
@@ skipping 2203 matching lines @@
         node->showTreeForThis();
 }
 
 void showNodePath(const WebCore::Node* node)
 {
     if (node)
         node->showNodePathForThis();
 }
 
 #endif