title: Sitecore - Hide a rendering if a placeholder is empty
body: <p>I have a fairly simple Sitecore MVC rendering which contains a heading field and a placeholder:</p>
  
  <pre><code>&lt;section&gt;
      &lt;div class="container"&gt;
          &lt;h2 class="m-header"&gt;&lt;span&gt;@Html.Sitecore().Field("PromoItemsHeader")&lt;/span&gt;&lt;/h2&gt;
  
          &lt;div class="l-section grid"&gt;
              @Html.Sitecore().Placeholder("PromoItems")
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/section&gt;
  </code></pre>
  
  <p>I would like this rendering to display outside of page-editing mode <em>only</em> if the placeholder contains items. This seems like it should be simple to do but I can't find an obvious / clean way of doing it.</p>