title: textarea's "required" attribute doesn't work even though the value is empty
body: <p>I created a simple page with list box and text area with conditions that all should be required.</p>
  
  <p>List box are working fine, but textarea box doesn't tell that the field is required to be filled.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;title&gt;Ratings &amp; Reviews&lt;/title&gt;
  &lt;body&gt;
  &lt;form&gt;
  
  &lt;span&gt;Customer Service*&lt;/span&gt;
  &lt;span&gt;
      &lt;select name=customer id=aa required&gt;
          &lt;option selected="rate" value="" disabled&gt;rate&lt;/option&gt;
          &lt;option value=1&gt;1&lt;/option&gt;
          &lt;option value=2&gt;2&lt;/option&gt;
          &lt;option value=3&gt;3&lt;/option&gt;
          &lt;option value=4&gt;4&lt;/option&gt;
          &lt;option value=5&gt;5&lt;/option&gt;
      &lt;/select&gt;
  &lt;/span&gt;
  &lt;br&gt;&lt;br&gt;
  &lt;span&gt;Value for money*&lt;/span&gt;
  &lt;span&gt;
      &lt;select name=money id=aa required&gt;
          &lt;option selected="rate" value="" disabled&gt;rate&lt;/option&gt;
          &lt;option value=1&gt;1&lt;/option&gt;
          &lt;option value=2&gt;2&lt;/option&gt;
          &lt;option value=3&gt;3&lt;/option&gt;
          &lt;option value=4&gt;4&lt;/option&gt;
          &lt;option value=5&gt;5&lt;/option&gt;
      &lt;/select&gt;
  &lt;/span&gt;
  
  &lt;div&gt;
      &lt;textarea name="reviews" rows=11 cols=50 maxlength=250 required&gt;
      &lt;/textarea&gt;
  &lt;/div&gt;
  
  &lt;div id=submit&gt;
      &lt;br&gt;
      &lt;input type=submit name=submit value=submit&gt;
  &lt;/div&gt;
  
  &lt;/form&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>