Fixes test flakiness on OS X Safari and Android when using jQuery 3.
Fixes #20182 more
Refs #20191

Instead of doing a new assert.async(), just do a single one for the entire test
and let the .then() be async as well.

Closes #20190

Closes #19906

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* Use $.one() instead of $.on() since there are no $.off()s in the code.
* Remove unnecessary namespacing of listeners for the `scroll` & `load` events.
    These are vanilla DOM events (not custom jQuery namespaced events)
    and we're not using jQuery namespacing to manage these event listeners either (e.g. `$.off()`).

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Fixes #19878

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When a DOM node is passed to an HTML tooltip, the `title` node is only
moved if it is not already in the tooltip. Otherwise, `empty()` is used
instead of `detach()` before appending the `title` to avoid memory
leaks. If a DOM node is passed to a plain text tooltip, its text is
copied via jQuery `.text()`.

Replaces `.detach()` with `.empty()`, as `.detach()` is almost never
useful but instead leaks memory. The difference between `empty` and
`detach` is that the latter keeps all the attached jQuery events/data.
However, since we do not return the previous children, the user would
have to keep these themselves, thus they can `detach()` if necessary.

This is a port of https://github.com/twbs/bootstrap/pull/14552 to v4.

Fixes #16828
Closes #16865

as role="menu" is a very specific (and strict) ARIA pattern for
desktop-like application menus, and our dropdowns are often used
as pure navigation dropdowns, this change abandons ARIA menus for
a more open-ended and light-weight approach
(see http://heydonworks.com/practical_aria_examples/#submenus and
http://www.w3.org/WAI/tutorials/menus/flyout/#improve-screen-reader-support-using-wai-aria)
note that in dropdown.js, switched to now target ``.dropdown-menu``
instead of ``role["menu"]`` - this also prevents bootstrap scripts
from "bleeding" into non-bootstrap components on the same page.
also removed the ``role=["listbox"]`` part, which appears to be
vestigial/unused (only place in bootstrap that uses that
role are carousels, and their key handling is done separately)

add modal my gawd