Support Github Gist embed codes
GitHub provides embed codes for Gists in this form, <script src="file.js"></script>. Slides throws an error when you try to use the script tag in an iframe. I didn't try editing the HTML of a text block but I am assuming this would also flag the same rule. It would be great to include these Gists as elements in addition to the code blocks in slides.
Embed a gist in an iframe reference: https://gist.github.com/Albert-W/e37d1c4fa30c430c37d7b1b1fe9b60d8
<head><base target='_blank' /></head>
That code will allow the Gist to show in Slides. However, there is a persistent error message (src data flagged and removed).