docs: static String safeName(String unsafeElementName) {
      String elementName = HtmlLexer.canonicalName(unsafeElementName);
  
      // Substitute a reliably non-raw-text element for raw-text and
      // plain-text elements.
      switch (elementName.length()) {
        case 3:
          if ("xmp".equals(elementName)) { return "pre"; }
          break;
        case 7:
          if ("listing".equals(elementName)) { return "pre"; }
          break;
        case 9:
          if ("plaintext".equals(elementName)) { return "pre"; }
          break;
      }
      return elementName;
    }