title: Orderby filter in angular.filter plugin doesn't seem to sort properly
body: <p>I'm using Angular Filter plugin to group the tr's in a table based on the "Row" parameter.</p>
  
  <p>Below code constructs the Tr according to Row value</p>
  
  <pre><code>&lt;tbody&gt;
        &lt;tr ng-repeat="row in data |groupBy: 'Row' | orderBy : 'Row'"&gt;
            &lt;td ng-repeat="person in row"&gt;{{person.Row}}.{{person.Label}}&lt;/td&gt;    
        &lt;/tr&gt;
  &lt;/tbody&gt;
  </code></pre>
  
  <p>But the 10th  and 11th item appears in the 2nd and 3rd row instead.
  How can I fix this ?</p>
  
  <p>Plnkr : <a href="http://plnkr.co/edit/GaW4XsAwlDkFs61VXkOl?p=preview" rel="nofollow">http://plnkr.co/edit/GaW4XsAwlDkFs61VXkOl?p=preview</a> </p>