New Twiddle

controllers.application.js

import Ember from 'ember';

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

controllers.index.js

import Ember from 'ember';

export default Ember.Controller.extend({
  greetings: undefined
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  beforeModel() {
		var receiveMessage = (event) => {
  		var origin = event.origin || event.originalEvent.origin; // For Chrome, the origin property is in the event.originalEvent object.
  		// Here you want to check origin, but in twiddle its null, try on ur machine...
      var data = event.data;
  		if (data.action !== undefined) {
        this.send(data.action);
      }
		}
    
    window.addEventListener("message", receiveMessage, false);
  },
  actions: {
    sayHi() {
      this.controllerFor('index').set('greetings', 'Hello there');
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.index.hbs

{{#if greetings}}<div>{{greetings}}</div>{{/if}}
<iframe src='https://4so.gennady.pp.ua/ember-iframe-test/iframe.html'></iframe>

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.0",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.0",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}