title: pug/jade refer to property by name
body: <p>I want to check if some property names are passed to the template based on a preset array:</p>
  
  <pre><code>- socialNames = ['facebook', 'twitter', 'instagram']
  each socialName in socialNames
      - social = this[socialName]
      if social 
          a(href=social.url)
              div
                  img.ug-profile-socials-
  icon(src=chrome.extension.getURL('public/socials/'+ social + '.png'))
              div
                  span.ug-profile-socials-followers !{social.followers}
  </code></pre>
  
  <p>The social = this[socialName] part is just the way I was expecting it to work, but it obviously does not. </p>