title: css grid property value invalid
body: <p>In both Chrome and Firefox nightly I get the following error when setting this property:</p>
  
  <pre><code>grid-template-columns: repeat(auto-fill);
  grid-template-rows: repeat(auto-fill, 1fr);
  </code></pre>
  
  <p><code>Invalid property value</code></p>
  
  <p>When looking at the <a href="https://www.w3.org/TR/css3-grid-layout/#repeat-syntax" rel="nofollow noreferrer">repeat()</a> syntax it seems that I entered it correctly? Both browsers still seem to somehow make it work, but it seems odd I'd get an error</p>