Window.clientInformation - missing alias for Window.navigator

[hamishwillee]

window.clientInformation is an alias of Window.navigator.

Historically this was non-spec but was present in Chrome (and others using same engine) and also Safari (since at least Feb 2017 according to whatwg/html#2379).
It was added to the spec here as a "legacy alias" in this PR,
FF91 just added it as an alias in https://bugzilla.mozilla.org/show_bug.cgi?id=1717072. It is default enabled (but there is a preference to allow it to be disabled easily if needed).

The question is, how is such a thing added to BCD?

I "think" I have to add this following the model of Window.scrollX which defines an alternative_name. I'll try that.

FYI, this is one of the items linked in #7585

[hamishwillee]

Closing this. Exploring it in basic PR #11690