polkitAuthenticationAgent.js: Fix dialog cancellation when

transitions are disabled.

When no transitions are allowed, _emitDone() ends up being called
too late causing two issues:

- The PolKit session instance is canceled in _destroySession(),
  causing its 'completed' signal to be fired. This runs the signal
  handler _onSessionCompleted(). Since this._doneEmitted hasn't
  been set yet the authentication attempt ends up being *restarted*
  internally.
- modalDialog.close() results in the AuthenticationDialog being
  disposed, causing this._emitDone() to fail on an invalid GObject.
  This results in Cinnamon never completing the polkit request.

Emit the 'done' signal immediately, so pkit isn't held up by anything
UI-related in Cinnamon.

Fixes linuxmint/mint22.1-beta#89

js/ui/polkitAuthenticationAgent.js

@@ -473,8 +473,8 @@ var AuthenticationDialog = GObject.registerClass({
 
     cancel() {
         this._wasDismissed = true;
-        this.close(global.get_current_time());
         this._emitDone(true);
+        this.close(global.get_current_time());
     }
 
     _onDialogClosed() {