title: hasClass('disabled') not working after .addClass('disabled')
body: <p>With selected the hasClass validation works correctly.</p>
  
  <pre><code>&lt;div class="row dis"&gt;
      &lt;input class="contact button selected" value="Contact Us"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <hr>
  
  <p>However if i remove the selected through jquery:</p>
  
  <pre><code>&lt;div class="row dis"&gt;
      &lt;input class="contact button" value="Contact Us"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <hr>
  
  <pre><code>if (!$('.dis &gt; .contact').hasClass('disabled')) {
      $("input.contact").click(function() {
  
          alert('---');
          $('.contact').addClass('disabled');
  
      });
  }
  </code></pre>
  
  <p>the hasClass still not find the disabled class after <code>$('.contact').addClass('disabled');</code>.</p>
  
  <p>So, i only want the first alert.</p>
  
  <p>Demo:</p>
  
  <p><a href="http://jsfiddle.net/dWGNJ/2/" rel="nofollow">http://jsfiddle.net/dWGNJ/2/</a></p>