Follows a link by name.
Will click the first link found with this link text by default, or a later one if an index is given. Match is case insensitive with normalized space. The label is translated label. There is an assert for successful click.
$label: Text between the anchor tags.
$index: Link position counting from zero.
Page on success, or FALSE on failure.
protected function clickLink($label, $index = 0) {
  $url_before = $this
    ->getUrl();
  $urls = $this
    ->xpath('//a[normalize-space(text())=:label]', array(
    ':label' => $label,
  ));
  if (isset($urls[$index])) {
    $url_target = $this
      ->getAbsoluteUrl($urls[$index]['href']);
  }
  $this
    ->assertTrue(isset($urls[$index]), t('Clicked link %label (@url_target) from @url_before', array(
    '%label' => $label,
    '@url_target' => $url_target,
    '@url_before' => $url_before,
  )), t('Browser'));
  if (isset($url_target)) {
    return $this
      ->drupalGet($url_target);
  }
  return FALSE;
}