tl;dr: What's the right way for a tag extension to execute JavaScript provided by the user? (On a private wiki without Internet access.)

Details: I run a private wiki for developers (not accessible from the Internet) that lets any wiki page author run JavaScript on a page by adding a tag:

<javascript> alert("hi"); </javascript>

(We understand the security implications, which is why the wiki isn't accessible by the world.) When we upgraded to MediaWiki 1.26 (from 1.24), a problem occurred: the <javascript> tag stopped recognizing the "mediawiki" and "mw" objects, but otherwise works. The following code reports an undefined variable "mw":

<javascript> mw.loader.using(....) </javascript>

I assume this is because the <javascript> extension builds a <script> tag as a string and uses the SkinAfterBottomScripts hook to add it to the page, rather than using ResourceLoader. However, I cannot figure out how to use ResourceLoader to add JavaScript provided on the wiki page like my small examples above. We can't use the array $wgResourceModules[$name]['scripts'] because the JavaScript isn't in a static file.

So... what's the right method for injecting author-supplied JavaScript in this manner?

I've already tried using ResourceLoader to add 'mediawiki' to $wgResourceModules[$name]['dependencies']. It didn't work, complaining that 'mediawiki' was not a known dependency. I also read https://www.mediawiki.org/wiki/ResourceLoader/Migration_guide_for_extension_... but did not find an answer.

Thanks for any advice! DanB