title: Get index in dart polymer repeat template
body: <p>I want to iterate over an enumerable and display a counter</p>
  
  <pre><code>&lt;div template repeat="{{ name in names }}"&gt;
    ###. {{name}}
  &lt;/div&gt;
  </code></pre>
  
  <p>What should I put instead of <code>###</code> so it shows the position of the name:</p>
  
  <pre><code>1. John Doe
  2. Jane Doe
  3. etc...
  </code></pre>