behat.inc.php

  /**
  * Sets an iFrame ID to no_name_iframe if there is no ID. You can then add a Switch to iFrame step after it using the na_name_iframe ID. 
  *
  * @Given /^I the set the iframe located in element with an id of "([^"]*)"$/
  */
  public function iSetTheIframeLocatedInElementWithAnIdOf($element_id) {
 
    $element = $this->getMainContext()->getSession()->getPage()->findById($element_id);
    if ($element == NULL) {
      throw new \Exception(sprintf("Element with ID '%s' not found", $element_id));
    }
    $javascript = <<<JS
          (function(){
            var elem = document.getElementById('$element_id');
            var iframes = elem.getElementsByTagName('iframe');
            var f = iframes[0];
            f.id = "no_name_iframe";
          })()
JS;
    $this->getMainContext()->getSession()->executeScript($javascript);
  }
}