title: Height animation in React Spring not working
body: <p>I've been animating scale with React Spring. The following works fine: </p>
  
  <pre><code>  &lt;ul&gt;
      {items.map((item, index) =&gt; {
        if (index === items.length - 1) {
          return (
            &lt;Spring
              key={item.id}
              from={{
                progress: 0,
              }}
              to={{
                progress: 1,
              }}
              config={{ delay: 300, duration: 300 }}
            &gt;
              {({ progress }) =&gt; {
                const style = { transform: `scale(${progress})` };
                return &lt;Item style={style} {...item} /&gt;;
              }}
            &lt;/Spring&gt;
          );
        }
        return &lt;Item {...item} /&gt;;
      })}
    &lt;/ul&gt;
  </code></pre>
  
  <p>However when I try and animate height from <code>0</code> to <code>auto</code> it doesn't work. Using console.log it seems that the <code>style</code> prop just returns <code>height: 'auto'</code> without any transitions. </p>
  
  <pre><code>  &lt;ul&gt;
      {items.map((item, index) =&gt; {
        if (index === items.length - 1) {
          return (
            &lt;Spring
              key={item.id}
              from={{
                height: 0
              }}
              to={{
                height: 'auto'
              }}
              config={{ delay: 300, duration: 300 }}
            &gt;
              {(style) =&gt; {
                console.log(style)
                return &lt;Item style={style} {...item} /&gt;;
              }}
            &lt;/Spring&gt;
          );
        }
        return &lt;Item {...item} /&gt;;
      })}
    &lt;/ul&gt;      
  </code></pre>