src/language-html/utils.js/inferScriptParser
function inferScriptParser(node, options) {
  if (node.name === "script" && !node.attrMap.src) {
    if (!node.attrMap.lang && !node.attrMap.type) {
      return "babel";
    }
    return _inferScriptParser(node);
  }

  if (node.name === "style") {
    return inferStyleParser(node) || "css";
  }

  if (options && isVueNonHtmlBlock(node, options)) {
    return (
      _inferScriptParser(node) ||
      inferStyleParser(node) ||
      getParserName(node.attrMap.lang, options)
    );
  }

  return null;
}