title: Javascript click event firing twice, even with stopPropagation
body: <p>I have a set of items like this:</p>
  
  <pre><code>&lt;label for="Cadenza-1" class="cars"&gt;
      &lt;input type="checkbox" value="1" alt="Cadenza" id="Cadenza-1" name="vehicles[]"&gt;
      &lt;img src="img/bill_murray_173x173.jpg"&gt;
      &lt;span&gt;Cadenza&lt;/span&gt;
  &lt;/label&gt;
  </code></pre>
  
  <p>there's about 13 of them. I want to add a class to the label when clicked. However, the click event fires twice. right now I'm debugging the click event then I'll add the class:</p>
  
  <pre><code>var cars = document.getElementsByClassName('cars');
  
  for(var c = 0;c &lt; cars.length; c++){
      cars[c].addEventListener("click", function(e){
          selectVehicle(cars[c],e);
      },false);
  }
  
  function selectVehicle(el,e) {
      console.log(e);
      e.stopPropagation();
  }
  </code></pre>
  
  <p>The <code>console.log</code> fires twice.</p>