Bug 1816395 - Fix intermittent browser_invitationDisplayNew.js. r=freaktechnik

Need some time to also give the notification time to have it's texts filled in by Fluent.

Differential Revision: https://phabricator.services.mozilla.com/D169798

--HG--
extra : amend_source : 0dc08329e809f9fbd226355b5e01662fb0a910f2

calendar/test/browser/invitations/browser_invitationDisplayNew.js

@@ -72,6 +72,7 @@ add_task(async function testShowPanelData() {
     .contentDocument.querySelector("calendar-invitation-panel");
 
   await panel.ownerDocument.l10n.ready;
+  await new Promise(resolve => requestIdleCallback(resolve));
 
   let notification = panel.shadowRoot.querySelector("notification-message");
   compareShownPanelValues(notification.shadowRoot, {