prototype extension bug

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

helpers.array.js

import Ember from 'ember';

export function array(params/*, hash*/) {
  return params;
}

export default Ember.Helper.helper(array);

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
{{#each (array "first-item" "second-item") as |item|}}
	<div>{{item}}</div>
{{/each}}

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {},
    "EXTEND_PROTOTYPES": false
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "beta",
    "ember-data": "2.7.0",
    "ember-template-compiler": "beta"
  },
  "addons": {}
}