When switching from 9.53 to 10.12 the banners ads stopped being displayed.

Since this commit(#13851) calling pbjs.renderAd() does not render BANNER ads anymore.
[deployed in 10.11.0]

https://github.com/prebid/Prebid.js/pull/13851/files#diff-b09bb69302f9e7c2a9de1ded930601d79326169d5a687af2822e07ce03e25275L327-L330

How it used to work:

1. you created iframe
2. then provided document object from this iframe to renderAd function like for example: pbjs.renderAd(iframe.contentWindow.document, bid.adId)
3. renderAd() would then take this iframe and write the BANNER ad into it

• Since this was now removed in commit Core: remove use of document.write in rendering #13851 if you pass iframes document into it, it will create double nested iframes and not display ads
• And if you provide window.document to it and element with ad-unit-id exists on the websites it will still not insert the iframe into that div element generated by renderAd()

@dgirardi is this expected behavior?