rem: return null; 
add: return new IFrameBuilder(); 
context: function createBuilder(implementation) {  switch(implementation) {    case "msxml3":    return new MSXMLBuilder("Msxml2.DOMDocument.3.0");        case "msxml4":    return new MSXMLBuilder("Msxml2.DOMDocument.4.0");    case "mozillaXML":    return new MozillaXMLBuilder();    case "svgplugin":    return new SVGPluginBuilder();    case "dom3ls":    return new DOM3LSBuilder();        case "iframe":    return new IFrameBuilder();  }  return null;}
meta: 7959	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/7959/056596486fb2832f049429354b7c4c4095f47b9a/DOMTestCase.js/clean/ecmascript/DOMTestCase.js