title: Unable to get current route instance in observers
body: <p>I am now with ember js. I need current route instance in controllers observer. I tried many links and searched a lot but still not able to get the route instance in observer method. 
  There is the code. </p>
  
  <pre><code>activeStagesChanged: Ember.observer('activeStages.[]', function () {
      let self = this;
  
      Ember.run.scheduleOnce('afterRender', function () {
        initCustomScrollbar('#status_timeline_box');
  
        self.handleAppStages(self.get('model'), self.get('currentUser.isConfirmAppStageChange'),
            Ember.getOwner(self).lookup('controller:application'));
      });
    })
  </code></pre>
  
  <p>Ember.getOwner(self).lookup('controller:application') this is the code that I assuming to return the route object.</p>