DomObject::global is a tricky API because it's used pervasively but has
subtle requirements that are not documented and not yet enforced by the
type system (#36116). The method returns the relevant global object for
a given DOM object, but that operation is only meaningful if there is an
active realm. We usually, but not always, have an active realm.
This change avoids a footgun by following the principle of least
surprise. Rather than making every single caller of `something.global()`
both prove that there is an active realm and think about which realm
they want active, we implement the obvious behaviour: always activate
the realm of the callee before obtaining the relevant global.
Testing: Existing WPT coverage is sufficient; this method is called all
over the codebase.
Fixes: #37070#27037
Signed-off-by: Josh Matthews <josh@joshmatthews.net>
3a04f4195e