Update Security FAQ about contextual menu navigations.

We have treated "right click > open in a new window" as similar to the
user copy-pasting the URL into a new window. As a result, many policies:
CSP / sandbox / COEP / COOP / Referrer / origin / browsing context group
/ ... are not inherited.

This is deliberate. As long as there are no strong evidences this could
harm users, we really shouldn't try doing something different. This
would:
- Add extra complexity and unresolved questions.
- Allow websites to block users from opening popups. We should consider
  the intents of the users superior to the intents of the website.
- Open up the door to countess opportunities to fill up new security
  bugs about: "What about inheriting xxx properties?".

There have been 20+ bug reports about this. They have all been closed as
Duplicated/WontFix. See:
- https://bugzilla.mozilla.org/show_bug.cgi?id=1784059
- https://issues.chromium.org/issues/40060542
- https://issues.chromium.org/issues/40057000
- https://issues.chromium.org/issues/324003975
- etc...

We should clear up the ambiguity to avoid additional
security shepherd work to triage the same kind of bug over and over. We
previously agreed with Mozilla to close and make them all public
(2022-08-30).

Bug: 324003975
Change-Id: I89ee125f3964690aadf7d9b0731bc575317f12f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5279395
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1259862}

• docs/security/faq.md[diff]