title: ipywidgets Textarea height='auto' does not work
body: <p>I am using ipywidgets to create a Dashboard with voila</p>
  
  <p>I have a Textarea as follows:</p>
  
  <pre><code>comm_text = widgets.Textarea(value='',
                              placeholder='OK',
                              description='',
                              style=style,
                              layout=widgets.Layout(height="auto", width="auto"))
  </code></pre>
  
  <p>what I pretend with height="auto" is that when entering lines in textarea the text box expands vertically accordingly. (I want to have all the text visible)</p>
  
  <p>It actually does not happend.
  As you can see in the screenshot I introduced 8 lines but the textarea does not expand along.</p>
  
  <p>Is that at all possible?
  If not, what does actually height="auto" stand for?</p>
  
  <p><a href="https://i.stack.imgur.com/sgprJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sgprJ.png" alt="out"></a></p>