This script will attach to a DOM node with a data-ref attribute of "async-responsive-iframe" value an iframe pointing to the provided data-url value.
It will also:
- style the iframe with no border and a 100% width
- use iframeResizer to style the height of the iframe to match the children document.
- communicate to the iframe using the postMessage API to send over the following data attributes [mail, countries, theme, site, group] as a