iframe within noscript rendering incorrectly.

Problem/Motivation

At some point along the way, it looks like Drupal changed how #markup was being filtered. In your module, you have the iframe being constructed like this:

$attributes = 'height="0" width="0" style="display:none;visibility:hidden;"';
$noscript = "<noscript><iframe src=\"{$src}\" {$attributes}></iframe></noscript>";

However if you look at the webpage output, the iframe is being rendered with the inline style attribute removed:

<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-XXXXXXX" height="0" width="0"></iframe></noscript>

This causes some accessibility issues because some screen readers will try to process the iframe.

Proposed resolution

Change the logic to build the iframe using the html_tag render type instead of trying to directly work with the html. The attached patch does that and in my testing the iframe is being output correctly again.