fix(conference-hangup): Leave room in parallel.

Currently we are waiting for the user to submit feedback dialog in
order to leave the room. Now the leave and showing the dialog are
executed in parallel.

conference.js

@@ -1061,13 +1061,6 @@ export default {
         return room.getSpeakerStats();
     },
 
-    /**
-     * Returns the connection times stored in the library.
-     */
-    getConnectionTimes() {
-        return room.getConnectionTimes();
-    },
-
     // used by torture currently
     isJoined() {
         return room && room.isJoined();
@@ -2445,7 +2438,7 @@ export default {
      * @param {string} [hangupReason] the reason for leaving the meeting
      * requested
      */
-    async hangup(requestFeedback = false, hangupReason) {
+    hangup(requestFeedback = false, hangupReason) {
         APP.store.dispatch(disableReceiver());
 
         this._stopProxyConnection();
@@ -2462,33 +2455,42 @@ export default {
 
         APP.UI.removeAllListeners();
 
-        let feedbackResult = {};
+        let feedbackResultPromise = Promise.resolve({});
 
         if (requestFeedback) {
-            try {
-                feedbackResult = await APP.store.dispatch(maybeOpenFeedbackDialog(room, hangupReason));
-            } catch (err) { // eslint-disable-line no-empty
-            }
-        }
+            const feedbackDialogClosed = (feedbackResult = {}) => {
+                if (!feedbackResult.wasDialogShown && hangupReason) {
+                    return APP.store.dispatch(
+                        openLeaveReasonDialog(hangupReason)).then(() => feedbackResult);
+                }
+
+                return Promise.resolve(feedbackResult);
+            };
 
-        if (!feedbackResult.wasDialogShown && hangupReason) {
-            await APP.store.dispatch(openLeaveReasonDialog(hangupReason));
+            feedbackResultPromise
+                = APP.store.dispatch(maybeOpenFeedbackDialog(room, hangupReason))
+                    .then(feedbackDialogClosed, feedbackDialogClosed);
         }
 
-        await this.leaveRoom();
+        const leavePromise = this.leaveRoom().catch(() => Promise.resolve());
+
+        Promise.allSettled([ feedbackResultPromise, leavePromise ]).then(([ feedback, _ ]) => {
+            this._room = undefined;
+            room = undefined;
+
+            /**
+             * Don't call {@code notifyReadyToClose} if the promotional page flag is set
+             * and let the page take care of sending the message, since there will be
+             * a redirect to the page anyway.
+             */
+            if (!interfaceConfig.SHOW_PROMOTIONAL_CLOSE_PAGE) {
+                APP.API.notifyReadyToClose();
+            }
+
+            APP.store.dispatch(maybeRedirectToWelcomePage(feedback.value ?? {}));
+        });
 
-        this._room = undefined;
-        room = undefined;
 
-        /**
-         * Don't call {@code notifyReadyToClose} if the promotional page flag is set
-         * and let the page take care of sending the message, since there will be
-         * a redirect to the page anyway.
-         */
-        if (!interfaceConfig.SHOW_PROMOTIONAL_CLOSE_PAGE) {
-            APP.API.notifyReadyToClose();
-        }
-        APP.store.dispatch(maybeRedirectToWelcomePage(feedbackResult));
     },
 
     /**
@@ -2498,7 +2500,7 @@ export default {
      * @param {string} reason - reason for leaving the room.
      * @returns {Promise}
      */
-    async leaveRoom(doDisconnect = true, reason = '') {
+    leaveRoom(doDisconnect = true, reason = '') {
         APP.store.dispatch(conferenceWillLeave(room));
 
         const maybeDisconnect = () => {