_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.

* 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

When one uses say a carousel inside a tab, the `.active` selector previously matches the carousel ones too leading to broken tabs.

It's not the perfect solution but should the job for now.

Ignore ESLint error in ie-emulation-modes-warning.js.

Although the error is valid, enough time has been spent on old IE's problems, so just ignore it.