Use a virtual scrollbar as this is simpler than having a real one (overflow: scroll doesn't seem to work in Phantom), and disable it for the new test.

One test has also been altered to prevent erroneous fails when other inline styles are added to the body (e.g. overflow).

When the body does not overflow (achieved by hiding the QUnit container), it should not be given a margin.

* Adjust margin for sticky elements on modal

Previously white space was visible to the right of sticky elements due to right padding being added to the body. This fixes #23661.

* Add unit tests for margin of sticky elements on modal

element

Part of an update to align the naming schemes across our components.

- Renames .popover-title to .popover-header
- Renames .popover-content to .popover-body

Refs: #22092

According to the docs, you just need to apply the `navbar-nav` to an
`<ul>` tag in a list-based navbar. In fact, `navbar-nav` seems to
override all the css properties set by `nav`.

Also, `nav-item` class should be used only for `<li>` tags, or in
conjunction with `<a>` tags to entirely avoid the list-based approach.

This commit removes the redundant `nav` class from `navbar-nav` `<ul>`
tags, moves `nav-item` from `<a>` tags to `<li>` tags and properly
adds `nav-item` class to `<li>` tags where missing.

Refs:

* https://v4-alpha.getbootstrap.com/components/navs/
* https://v4-alpha.getbootstrap.com/components/navbar/#nav

* Add carousel mouse listeners even if touch events enabled

- touch events are enabled not just on "mobile", just also on
touch-enabled desktop/laptop devices; additionally, it's possible to
pair a mouse with traditionally touch-only devices (e.g. Android
phones/tablets); currently, in these situations the carousel WON'T pause
even when using a mouse

* Restart cycle after touchend

as `mouseenter` is fired as part of the touch compatibility events, the
previous change results in carousels which cycle until the user
tapped/interacted with them. after that they stop cycling (as
`mouseleave` is not sent to the carousel after user scrolled/tapped
away).
this fix resets the cycling after `touchend` - essentially returning
to the previous behavior, where on touch the carousel essentially never
pauses, but now with the previous fix it at least pauses correctly for
mouse users on touch-enabled devices.
includes documentation for this new behavior.

* Remove aria-expanded from collapse.js target element

aria-expanded="true"/aria-expanded="false" only applies to the trigger,
not the element that is being expanded/collapsed.

* Tweak collapse.js accessibility section

...to make it clearer that the aria-expanded attribute always just goes
on the control.

* Fix collapse.js unit tests

- reword some of the text to make it clear we're checking behavior of
trigger/control
- move incorrect aria-expanded out of the <div>s and to the actual
trigger/control <a>s
- fix incorrect test assertion text output false -> true

* Only change aria-pressed if it's not an input-based radio or checkbox group

aria-pressed="true"/aria-pressed="false" is really only useful for
making on/off toggles out of, say, `<button>` elements. the attribute is
useless (and potentially confusing/conflicting) on, say, `<label>`
elements for an existing `<input type="radio">` or similar.

* Add unit test for buttons.js and radio/checkbox inputs in button groups

Fix accordion behavior with JQuery interface

Carousel - Add attributes from and to for Slid and Slide events

* Allow to use Tab.js with list-group

* Allow to use list-group with div parent instead of an ul parent