We don't support Opera 12, and Firefox's property was the unprefixed one.

Unit test for pull request #24240

Fix for issue #24117

Having it uppercase doesn't offer anything and the lowercase version slightly improves gzip compression.

* Offset option can be function (Popper.js)

* Fix...add function type for offset option

* Remove constants for popper config

* Optimize code. Remove foreach loop.

* Refactoring. Remove getOffset method

We can check for browser compatibility on lint time now.

* use a trailing slash when possible
* use https when possible
* remove a few redirected links
* consistently use `https://popper.js.org/`
* fix `iconUrl` in nuget files
* change Jekyll Windows guide to the official one

* Use `aria-selected` instead of `aria-expanded`
* Change tab.js to use `aria-selected` rather than `aria-expanded`
* Add `aria-orientation=vertical` to vertical tab list
* Remove dynamic tabs with dropdowns
* Fix non-interactive code examples
* Only set `aria-selected` on the `role="tab"` trigger - this stops `aria-selected` being incorrectly added to the `role="tabpanel"` itself (probably harmless, but nonetheless incorrect)

* fix(scrollspy): Handle nested navs when nav-link inside nav-item

* [scrolspy] Find only child .nav-link's inside .nav-item

* [scrollspyt] Add tests for nested navs with nav-link inside nav-item

* fix troy-o's in test

_adjustDialog should be called when the modal is first displayed to prevent it jumping position when the viewport is resized

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).

Prevents the test from failing

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