Fix LoginDialog hidden by gUM-Overlay (#766)

* Fix LoginDialog hidden by gUM-Overlay

Running FF46 on Linux and Android. The gUM Dialog (zIndex 1013) hides the LoginDialog (zIndex 999 by default) , but the gUM Dialog will only be resolved when connection is completed (aka hideUserMediaPermissionsGuidanceOverlay is called once the Promise.all in createInitialLocalTracksAndConnect is resolved and that Promise includes "connect").

Fix this by increasing the connection dialog zIndex.

Alternatively this could by fixed by handling gUM and connection one after the other.

* remove whitespace change

modules/UI/authentication/LoginDialog.js

@@ -113,7 +113,8 @@ function LoginDialog(successCallback, cancelCallback) {
         states,
         {
             closeText: '',
-            persistent: true
+            persistent: true,
+            zIndex: 1020
         },
         null
     );