Steps to replicate the issue (include links if applicable):

• open a page with a map in visual editor

What happens?:
The map preview does not show tiles or geoforms.

What should have happened instead?:
There should be a complete preview of the map.

Other information (browser name/version, screenshots, etc.):
https://en.wikipedia.beta.wmflabs.org/w/index.php?title=Maptests/Maki_7_migration&action=edit