<!DOCTYPE html>
<html>
<head>
  <title>Bug 336147</title>
</head>
<body>
  <form action="http://foo.com/" method="post">
    <input value="abc" type="button" id="fooButton">
  </form>
  <script>
    document.getElementById('fooButton').innerHTML = 'xyz';
  </script>
</body>
</html>