How to make es6 import start working using tern_for_vim

Question

I've installed tern_for_vim, configured everything using also .tern-project:

{
  "plugins": {
    "node": {},
    "es_modues": {}
  },
  "libs": [
    "ecma5",
    "ecma6",
    "browser",
    "ecmascript",
    "react",
    "underscore"
  ],
  "ecmaVersion": 6
} 

and now, when I try to import let's say underscore in this way:

underscore = require('underscore')

autocompletion for underscore. works perfectly, but when I import in a modern way:

import underscore from 'underscore' 

autocompletion for underscore. doesn't work. How to fix it? Any clues?