Comment by simonw

Whoa... it looks like the Firefox HTML5 parser is still maintained as Java to this day!

Here's the relevant folder:

https://github.com/mozilla-firefox/firefox/tree/main/parser/...

  make translate        # perform the Java-to-C++ translation from the remote
                        # sources

And active commits to that javasrc folder - the last was in November: https://github.com/mozilla-firefox/firefox/commits/main/pars...