Firefox Select Issue

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  selectedVal: 3,
  options: [
    { value: 1, text: 'foo', disabled: false},
    { value: 2, text: 'bar', disabled: false},
    { value: 3, text: 'baz', disabled: false}       
  ],
  actions: {
    getNewOptions() {
  		this.set('options', [
    	  { value: 1, text: 'foo', disabled: false},
   		 	{ value: 2, text: 'bar', disabled: true},
   		 	{ value: 3, text: 'baz', disabled: false}   
    	]);
  	}
  }
});

helpers.if-cond.js

import Ember from 'ember';

export function ifCond(options) {
  var v1 = options[0];
  var operator = options[1];
  var v2 = options[2];

  switch (operator) {
      case '==':
          return (v1 == v2);
      case '===':
          return (v1 === v2);
      case '<':
          return (v1 < v2);
      case '<=':
          return (v1 <= v2);
      case '>':
          return (v1 > v2);
      case '>=':
          return (v1 >= v2);
      case '&&':
          return (v1 && v2);
      case '||':
          return (v1 || v2);
      default:
          return false;
  }
}

export default Ember.Helper.extend({ compute: ifCond });

templates.application.hbs

<select onchange={{action (mut selectedVal) value="target.value"}}>
  <option value="">Please select option...</option>
  {{#each options key="value" as |option|}} 
    <option value={{option.value}} selected={{if-cond option.value '===' selectedVal}} disabled={{option.disabled}}>{{option.text}}</option>
  {{/each}}
</select>
<br/>
<button {{action "getNewOptions"}}>Get New Options</button>

twiddle.json

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