How to put eToys projects in a browser to run, like Illinois?

I'd like to run eToys projects through a browser, like Illinois has
done  with their Library Collections -
http://etoysillinois.org/library?tags=CS4K5%20Grade%201

How do they do this.  It looks like with the eToys plugin, clicking on
the link to the project in my browser will open up eToys software.
The Illinois version looks like it's running within the browser, that
looks like a better way.

Scratch has this capability with a jar file to include in the website's folder.

Thanks for any help,
Randy Latimer