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