observers[index] FF bug

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  watch: null,
  updatedText: function(){
  	console.log('we dont get here in firefox')
	}.observes('watch')
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
});

templates.application.hbs

<h1>Tick the box and check the console in firefox</h1>
<br>
<br>
{{input checked=checked type="checkbox"}}
{{my-component watch=checked}}
<br>
<br>

twiddle.json

{
  "version": "0.10.7",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "canary",
    "ember-data": "2.10.0",
    "ember-template-compiler": "canary",
    "ember-testing": "canary"
  },
  "addons": {}
}