Thread:Project:Support desk/RessourceLoader: Custom Javascript not applied in edit preview

I have some javascript similar to User:Subfader/vector.js added in my MediaWiki:Common.js.

It affects article content and works fine but not when I preview text. It seems to be fixed in MW 1.19 as it works on mediawiki.org but not on my wiki (MW 1.18.0). How can it be fixed without upgrading?