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

Source/core/dom/Node.idl

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
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     boolean            hasChildNodes();
     [CustomElementCallbacks, PerWorldBindings]
     Node               cloneNode(optional boolean deep);
     [CustomElementCallbacks] void normalize();
 
     // Introduced in DOM Level 2:
     [MeasureAs=NodeIsSupported] boolean isSupported([Default=Undefined] optional DOMString feature,
                                                     [TreatNullAs=NullString,Default=Undefined] optional DOMString version); // Removed in DOM4.
 
     [TreatReturnedNullStringAs=Null, PerWorldBindings, MeasureAs=NodeNamespaceURI] readonly attribute DOMString namespaceURI; // Moved to Element and Attr in DOM4.
-    [TreatReturnedNullStringAs=Null, TreatNullAs=NullString, PerWorldBindings, RaisesException=Setter, MeasureAs=NodePrefix] attribute DOMString prefix; // Moved to Element and Attr in DOM4.
     [TreatReturnedNullStringAs=Null, PerWorldBindings, MeasureAs=NodeLocalName] readonly attribute DOMString localName; // Moved to Element and Attr in DOM4.
 
     // Introduced in DOM Level 3:
     [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString baseURI;
 
     [TreatReturnedNullStringAs=Null, TreatNullAs=NullString, PerWorldBindings, CustomElementCallbacks] attribute DOMString textContent;
 
     [MeasureAs=NodeIsSameNode] boolean isSameNode([Default=Undefined] optional Node other); // Removed in DOM4.
     boolean isEqualNode(Node other);
     [TreatReturnedNullStringAs=Null] DOMString lookupPrefix([TreatNullAs=NullString] DOMString namespaceURI);
     boolean isDefaultNamespace([TreatNullAs=NullString] DOMString namespaceURI);
     [TreatReturnedNullStringAs=Null] DOMString lookupNamespaceURI([TreatNullAs=NullString] DOMString prefix);
 
     // DocumentPosition
     const unsigned short      DOCUMENT_POSITION_DISCONNECTED = 0x01;
     const unsigned short      DOCUMENT_POSITION_PRECEDING    = 0x02;
     const unsigned short      DOCUMENT_POSITION_FOLLOWING    = 0x04;
     const unsigned short      DOCUMENT_POSITION_CONTAINS     = 0x08;
     const unsigned short      DOCUMENT_POSITION_CONTAINED_BY = 0x10;
     const unsigned short      DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC = 0x20;
 
     unsigned short compareDocumentPosition(Node other);
 
     // Introduced in DOM4
     [ImplementedAs=bindingsContains] boolean contains(Node other);
 
     // IE extensions
     [PerWorldBindings] readonly attribute Element parentElement;
 };