Fix using Buffer on window scope (#6324)

* Update 2fa.vue

* Import 'core-js/es/typed-array/from'

* Bye polyfill

src/client/pages/my-settings/2fa.vue

@@ -208,11 +208,11 @@ export default Vue.extend({
 						challengeId: registration.challengeId,
 						stage: 0,
 						publicKeyOptions: {
-							challenge: Buffer.from(
-								registration.challenge
-									.replace(/\-/g, "+")
-									.replace(/_/g, "/"),
-								'base64'
+							challenge: Uint8Array.from(
+								atob(registration.challenge
+									.replace(/\-/g, '+')
+									.replace(/_/g, '/')),
+								x => x.charCodeAt(0),
 							),
 							rp: {
 								id: hostname,