[keycloak-dev] Let the check-sso feature of the javascript adapter do the check in hidden iframe

[Niko Köbler]

Hi all / Stian,

based on the discussion in https://github.com/keycloak/keycloak/pull/5932, I created a new Jira issue and a PR (wip) with a first approach.
I'd like to discuss, if this yields into the right direction.

Regards,
- Niko