I like to see es6 source map

I would like to see the code written in es6 syntax. But I get something like this

define('simple-ember/app', ['exports', 'ember', 'ember/resolver', 'ember/load-initializers', 'simple-ember/config/environment'], function (exports, Ember, Resolver, loadInitializers, config) {

  'use strict';

  var App;

  Ember['default'].MODEL_FACTORY_INJECTIONS = true;

  App = Ember['default'].Application.extend({
    modulePrefix: config['default'].modulePrefix,
    podModulePrefix: config['default'].podModulePrefix,
    Resolver: Resolver['default']
  });

  loadInitializers['default'](App, config['default'].modulePrefix);

  exports['default'] = App;

});

I would like to see it

import Ember from 'ember';
import Resolver from 'ember/resolver';
import loadInitializers from 'ember/load-initializers';
import config from './config/environment';

var App;

Ember.MODEL_FACTORY_INJECTIONS = true;

App = Ember.Application.extend({
  modulePrefix: config.modulePrefix,
  podModulePrefix: config.podModulePrefix,
  Resolver: Resolver
});

loadInitializers(App, config.modulePrefix);

export default App;

how can I get this behavior by ember-cli? I tried various manipulations sourcemaps option and babel plugin, but to no avail.