No functional changes - we can still very easily get to the global
object via `Realm::global_object()`. This is in preparation of moving
the intrinsics to the realm and no longer having to pass a global
object when allocating any object.
In a few (now, and many more in subsequent commits) places we get a
realm using `GlobalObject::associated_realm()`, this is intended to be
temporary. For example, create() functions will later receive the same
treatment and are passed a realm instead of a global object.
This is an editorial change in the Intl spec:
7c13db4
This also normalizes the spelling of the "Internal slots" heading in
Intl.Collator, which is another editorial change in the Intl spec:
ec064bd
