title: Required tag in select field doesn't work
body: <p>I try to add the required attribute to my select tag. Unfortunately this is simply ignored. The drop down list is filled dynamically from database entries. Does anyone know why? Is the dynamic elements to blame?</p>
  
  <pre><code>&lt;div class="input-field col s12 m6 l6"&gt;
      &lt;?php
      //-------------------------------------------//
      $statement = $pdo-&gt;prepare("SELECT * FROM availableCards WHERE Active = '1' ORDER BY Description");
      $statement-&gt;execute();
      echo '&lt;select name="images" id="images" required&gt;';
      echo '&lt;option value="" disabled selected&gt;Bitte wählen&lt;/option&gt;';
      while ($data = $statement-&gt;fetchAll(PDO::FETCH_ASSOC)) {
          foreach ($data as $row) {
              echo '&lt;option name="' . $row['Value'] . '" value="' . $row['Value'] . '" data-icon="../cards/' . $row['ImagePath'] . '"&gt;' . $row['Description'] . '&lt;/option&gt;';
          }
      }
      echo '&lt;/select&gt;';
      //-------------------------------------------//
      ?&gt;
      &lt;label for="images"&gt;Karte auswählen&lt;/label&gt;
  &lt;/div&gt;
  </code></pre>