helper returning dom

controllers.application.js

import Ember from 'ember';

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

helpers.image-tag.js

export default Ember.Helper.helper(function (params) {
  var img = new Image();
  img.src = params[0];
  return img;
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{image-tag "https://www.google.com/images/srpr/logo11w.png"}}
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.4.8",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.8/ember.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.9/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.8/ember-template-compiler.js"
  }
}