New Twiddle

controllers.application.js

import Ember from 'ember';

const FooMixin = Ember.Mixin.create({
  go() {
    this._super(...arguments);
    console.log('foo mixin');
  }
});

const BarMixin = Ember.Mixin.create({
  go() {
    this._super(...arguments);
    console.log('bar mixin');
  }
});

const SomeClass = Ember.Object.extend({
  go() {
    console.log('some class');
  }
})

const SomeExtendedClass = SomeClass.extend(FooMixin, BarMixin, {});

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  blah: SomeExtendedClass.create(),
  
  actions: {
    callGo() {
      this.get('blah').go();
    }
  }
});

templates.application.hbs

<button {{action 'callGo'}}>Call Go</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}