Bug 1484048 - Part V, Re-enable UA Widget on Desktop Nightly r=smaug

Backed out changeset fd0d6079d0d2

Differential Revision: https://phabricator.services.mozilla.com/D3665

--HG--
extra : moz-landing-system : lando

modules/libpref/init/all.js

@@ -1384,7 +1384,7 @@ pref("dom.event.highrestimestamp.enabled",  true);
 pref("dom.event.coalesce_mouse_move",       true);
 
 #if defined(NIGHTLY_BUILD) && !defined(ANDROID)
-pref("dom.ua_widget.enabled", false);
+pref("dom.ua_widget.enabled", true);
 #else
 pref("dom.ua_widget.enabled", false);
 #endif