The function transformToXML has a problem with the meta content type tag. It outputs it like this:

    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

which is not correct X(HT)ML, because it closes with '>' instead of with '/>'.

A way to get the output correct is to use instead of transformToXML first transformToDoc anf then saveHTML:

    $domTranObj = $xslProcessor->transformToDoc($domXmlObj);
    $domHtmlText = $domTranObj->saveHTML();