title: Directive doesn't update parents scope
body: <p>all the code <a href="http://jsfiddle.net/mato75/o9e3cb56/" rel="nofollow">http://jsfiddle.net/mato75/o9e3cb56/</a></p>
  
  <p>directive: </p>
  
  <pre><code>scope: { attrs: '=?' }
  </code></pre>
  
  <p>main ctrl:</p>
  
  <pre><code>this.val = { val: '1', title: '2' };
  
  $scope.$watch(angular.bind(this, function () { return this.val.title }), function () {
       doSomethingOnChange()
  });
  </code></pre>
  
  <p>html:</p>
  
  <pre><code>&lt;div dirc x-attrs="ctrl.val"&gt;
  </code></pre>
  
  <p>When I change title in directive, main controllers watch is not dispatched.</p>