ES6+ in Cloud Functions for Firebase - preset-2015 with async/await (not getting compiled)

CF4F-ES6-2|function03.js

// Babel output - with Babel REPL settings:
// * preset-es2015
"use strict";

var functions = require("firebase-functions");

var message = function message() {
  return new Promise(function(resolve) {
    setTimeout(function() {
      resolve("from Babelified Cloud Functions!");
    }, 5000);
  });
};

module.exports.helloWorld = functions.https.onRequest(async function(req, res) {
  var world = await message();
  res.status(200).send("Hello " + world);
});