Dropdown's arrow key handler runs global DOM query?

[cvrebert]

It seems rather odd that we're selecting all the dropdown items in the entire document in

bootstrap/js/src/dropdown.js

Line 233 in 2f17682

let items = $.makeArray($(Selector.VISIBLE_ITEMS))

Surely we should be limiting the query to the descendants of the relevant dropdown menu? It seems rather unnecessarily wasteful otherwise.

[mdo]

Merged #19953, so closing.