With current `000-tor-browser.js` prefs default theme extensions are not installed. `AddonManager.maybeInstallBuiltinAddon` is used to install these, which requires enabledScopes to have flag 4 (application scope). So changing `extensions.enabledScopes` from 1 to 5 fixes this. My understanding is that this should only allow installing extensions from application directory, which we control. Is there any reason not to do this change? Also, some related prefs seem obsolete: ``` extensions.bootstrappedAddons extensions.enabledAddons extensions.enabledItems ``` We could also use this to clean them up.