The "https://creativecommons.org/choose/" iframe is hardcoded as HTTPS. This becomes a problem when a user is installer MediaWiki on an HTTP server.
Results in the following in Chrome 45:
Mixed Content: The page at 'https://creativecommons.org/choose/?partner=MediaWiki&exit_url=http%3A%2F%2…t=http%3A%2F%2Fmediawiki%2Fw%2Fmw-config%2Fconfig-cc.css' was loaded over HTTPS, but requested an insecure stylesheet 'http://mediawiki.dev/w/mw-config/config-cc.css'. This request has been blocked; the content must be served over HTTPS.
We should load creativecommons over HTTP instead of HTTPS. Most likely by using a protocol relative url.