title: role="alert" is only working for the first time
body: <p>I have added the following piece of code to make screen reader read the alert message:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;aside aria-live="assertive" aria-atomic="true" role="alert" ng-show="login.hasWarning();" translate="{{message}}"&gt;&lt;/aside&gt;
  
  &lt;form&gt;
    &lt;!--form content--&gt;
  &lt;/form&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>It works perfectly for the first time, however when I commit the error again, it doesn't reads the updated error message again. What am I missing?</p>