When using the WebViewMainActivity for passkey registration, the webpage fails during the registration process with an error indicating that base64url is not defined.

This seems to stem from the fact that the demo HTML or JS does not define or include a polyfill for base64url, which is not a standard global in JavaScript. Browsers do not natively support base64url as a global object, and it needs to be defined manually or provided via a library or helper function. This is probably an error in the glitch page version: https://credman-web-test.glitch.me/

Steps to Reproduce:

Launch the WebView using WebViewMainActivity.

Trigger a new passkey registration.

Observe the JS error in the WebView console related to base64url being undefined.