[Partitioned Popins] Test RSA in popin iframe
We should ensure this works too since it is a distinct path more akin to
current behavior.
Explainer: https://explainers-by-googlers.github.io/partitioned-popins/
I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/ApU_zUmpQ2g/
Bug: 340606651
Change-Id: Ia2caaff7c4a4c94964f52b0c1c68522ea9d53863
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5962521
Auto-Submit: Ari Chivukula arichiv@chromium.org
Commit-Queue: Sandor «Alex» Major sandormajor@google.com
Reviewed-by: Sandor «Alex» Major sandormajor@google.com
Cr-Commit-Position: refs/heads/main@{#1373486}