[Partitioned Popins] The opener cannot open more than one popin
Only one popin can be open at a time for a given tab.
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: I18ad78d6959497a5763c9d51bba17b586aa61479
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5823949
Auto-Submit: Ari Chivukula arichiv@chromium.org
Reviewed-by: Nasko Oskov nasko@chromium.org
Commit-Queue: Ari Chivukula arichiv@chromium.org
Cr-Commit-Position: refs/heads/main@{#1349396}