title: Observer not getting triggered on checkbox checked property when testing in IE-8
body: <p>Hi there my dear community members. I am having an issue only in IE 8 when testing for handling checkbox click events. Here is a JSBIN link where you can see the issue : <a href="http://jsbin.com/jicijilo/1/" rel="nofollow">http://jsbin.com/jicijilo/1/</a></p>
  
  <p>Sorry that I had to inject whole of the mocha adapter and expectjs source codes in them because apparently only mozilla can handle raw sources like these <a href="https://raw.githubusercontent.com/teddyzeenny/ember-mocha-adapter/master/adapter.js" rel="nofollow">https://raw.githubusercontent.com/teddyzeenny/ember-mocha-adapter/master/adapter.js</a></p>
  
  <p>The test itself is very simple, I have a list of questions and each question has active attribute which is boolean. I have a header checkbox that toggles this "active" attribute of all the questions. In ie8 however, when we click on the checkbox using click helper, the observer doesn't seem to be getting triggered! Here is the core code for the test:</p>
  
  <pre><code>    &lt;script&gt;
        //APPLICATION CODE STARTS HERE
          window.AS = Ember.Application.create({
              rootElement: '#ember-testing'
          });
          mocha.setup('bdd');
  
          Ember.onLoad('Ember.Application', function(Application) {
  
              Application.initializer({
                  name: 'tests',
                  initialize: function(container, application) {
                      Ember.testing = true;
                  }
  
              });
          });
  
  
          Ember.Test.adapter = Ember.Test.MochaAdapter.create();
          AS.setupForTesting();
          AS.ApplicationAdapter = DS.FixtureAdapter.extend({simulateRemoteResponse: false});
          AS.injectTestHelpers();
          AS.Router.map(function() {
              this.resource('questions', {path: '/'});
          });
  
          AS.Question = DS.Model.extend({
              name: DS.attr('string'),
              active: DS.attr('boolean')
          });
  
          AS.Question.FIXTURES = [
              {
                  "id": 1,
                  "name": "What is your age?",
                  "active": false
              },
              {
                  "id": 2,
                  "name": "What is your name?",
                  "active": false
              }
          ];
  
          AS.QuestionsRoute = Ember.Route.extend({
              model: function(params) {
                  return this.get('store').find('question');
              }
          });
  
          AS.QuestionsController = Ember.ArrayController.extend({
            toggleAll: false,
            onToggleAllChange: function(){
              var toggleAll = this.get("toggleAll");
              this.get('content').forEach(function(question){
                question.set("active", toggleAll);
              });
            }.observes('toggleAll')
          });
  
          &lt;/script&gt;
  
  
  
      &lt;script&gt;
  
          describe("Testing", function() {
  
  
              beforeEach(function() {
                  AS.reset();
                  visit("/");
              });
  
              it("test header toggle", function() {
  
                  click($("input[name='toggleAll']")).then(function() {
                      var chkd = $("input[name='toggleAll']")[0].checked;
                      $(".question input").each(function(index, dom){
                        expect(dom.checked).to.be(chkd);
                      });
                  });
              });
          });
  
          $(document).ready(function() {
              mocha.run();
          });
  
      &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
      &lt;script type="text/x-handlebars" data-template-name="questions"&gt;
          &lt;div&gt;{{input type="checkbox" name="toggleAll" checked=toggleAll}} Toggle active&lt;/div&gt;  
          {{#each}}
               &lt;div class="question"&gt;{{input type="checkbox" checked=active}} {{name}}&lt;/div&gt;
          {{/each}}
      &lt;/script&gt;
  
      &lt;div id="mocha"&gt;&lt;/div&gt;
      &lt;div id="ember-testing" style="border:1px solid #CCC;"&gt;&lt;/div&gt;
  &lt;/body&gt;
  </code></pre>
  
  <p>The test fails in ie8 but if you were to click on the checkbox manually, the observer does get triggered. Your help will be much appreciated. Thanks, Dee</p>