Serialize form and not the children separately

[bjoern-tantau]

If a form with data-remote=true is serialized elements inside fieldsets will be serialized twice if you call serializeArray on the forms children instead of on the form itself.

With the html

<form>
  <fieldset>
    <input type="text" name="foo" value="bar" />
  </fieldset>
</form>

$($('form')[0].elements).serializeArray();
// Outputs [ { name: 'foo', value: 'bar' }, { name: 'foo', value: 'bar' } ]
$($('form')[0]).serializeArray();
// Outputs [ { name: 'foo', value: 'bar' } ]