Browser Redirect in Mac Catalyst

Describe the bug
When authenticating in a Mac Catalyst app, the user is switched to Safari instead of redirecting back to the app. The authentication completes successfully and the callback completes successfully. However, the user flow switches to Safari. This is confusing to the user.

To Reproduce
Steps to reproduce the behavior:

1. Download the AppAuth Example-iOS_ObjC code. Enable configure for Google OpenID provider, enable Mac Catalyst and build for My Mac.
2. Launch and tap "Authorize". The app opens a confirmation.
   3, Confirm the authentication, the app opens the Google authentication web view window.
3. Complete the authentication process for Google
4. The user is switched to Safari after authenticating. No new tab is opened.
5. However, the authentication completes successfully and the callback is called.

Expected behavior
The user is switched back to the app.

Desktop (please complete the following information):

• OS: MacOS Catalina 10.15.2
• Browser : Safari
• Version : 1.3.0

Start with the AppAuth Example-iOS_ObjC reproduction configured for Google OpenID and Mac Catalyst, then trace the browser redirect and callback handling. Done means authentication still completes, but the user returns to the app instead of being left in Safari.