HtmlFile:test.html
  PsiElement(HTML_DOCUMENT)
    PsiElement(XML_PROLOG)
      PsiElement(XML_PROCESSING_INSTRUCTION)
        XmlToken:XML_PI_START('<?')
        XmlToken:XML_PI_TARGET('xml version='1.0'')
        XmlToken:XML_PI_END('?>')
      PsiWhiteSpace('\n  ')