Active language related extensions are not listed in the extension debug menu

[vanesa]

Steps to reproduce:

1. Have the browser extension for Chrome active. On GitHub, run localStorage.debug=true;location.reload() in your console if the extension debug menu isn't visible already.
2. Click on the menu and notice that all active language extensions are missing from the list.

Expected behavior:

Show all of my active extensions.

Actual behavior:

Only shows the non-language related extensions.

[vanesa]

Language extensions appear on the list when the user is looking at a file on GitHub that requires the necessary language extension to activate.