Flexible Images in Infobox

I'm trying to display an image with flexible dimensions in Cesium's infobox. As such, we don't include height / width / min-height / min-width on it.

Unfortunately, Cesium finishes resizing the iframe before the image itself loads, and thus leaves me with an infobox 8 pixels tall.

I have tried to include some JS within the infobox to act on this, but it isn't triggering when the infobox loads either.

1) Is there some way to trigger Cesium's infobox to re-evaluate the logic it uses in _descriptionSubscription again, and thus allow it to handle the correct size once the image has loaded?

2) Alternatively, is there some way to have JS trigger from within the infobox when it loads, or some event I can trigger code on? [I have tried both using allow-scripts, and removing the sandbox tag altogether.]

I know updating the description property triggers an infoBox resize. Perhaps you can use that? Here’s a thread that talks more about this: