Bug 1865787 - Add missing fluent files to aboutAddonsExtra.js. r=mkmelin

Differential Revision: https://phabricator.services.mozilla.com/D194605

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

mail/base/content/aboutAddonsExtra.js

@@ -27,6 +27,8 @@ XPCOMUtils.defineLazyPreferenceGetter(
 );
 
 (async function () {
+  window.MozXULElement.insertFTLIfNeeded("branding/brand.ftl");
+  window.MozXULElement.insertFTLIfNeeded("toolkit/about/aboutAddons.ftl");
   window.MozXULElement.insertFTLIfNeeded("messenger/aboutAddonsExtra.ftl");
   // Needed for webext-perms-description-experiment.
   window.MozXULElement.insertFTLIfNeeded("messenger/extensionPermissions.ftl");