title: Polymer determine the last item on dom-repeat items
body: <p>I'm trying to create breadcrumbs from an array of strings.
  I have an array property called <code>taxonomy</code> and it looks like the <code>["categories", "clothing", "men", "suits"]</code>. Using <code>dom-repeat</code> like this:</p>
  
  <pre><code>&lt;template is="dom-repeat" items="{{taxonomy}}" id="breadcrumbs"&gt;
    &lt;span&gt;{{item}}&lt;/span&gt;&lt;span hidden$="[[computeSpanHidden]]"&gt; &gt; &lt;/span&gt;
  &lt;/template&gt;
  </code></pre>
  
  <p>The resulting view looks like this:</p>
  
  <p><strong>categories > clothing > men > suits ></strong></p>
  
  <p>What i would like is to remove the last <strong>></strong> to get something like this:</p>
  
  <p><strong>categories > clothing > men > suits</strong></p>
  
  <p>I have tried doing this by binding to the hidden attribute of the span i want to hide but I am stuck. The incomplete <code>computeSpanHidden</code> function looks like this:</p>
  
  <pre><code>computeSpanHidden: function(){
    if(this.taxonomy.slice(-1)[0] == /**the value i want to know how to get **/)
      { return true; } 
        else 
          { return false; }
  }
  </code></pre>