Modal Tab Behavior Different Than Sky UX 1

[Blackbaud-TrevorBurch]

Expected behavior

In Sky UX 1 when you tab throughout a modal when it reaches the end of the contents it will tab back up to the top of the modal.

Actual behavior

In Sky UX 2 when you tab to the end of the modal it will tab into the address bar of the browser and then will tab through things behind the modal before it tabs back to the top of the modal

Steps to reproduce

Visible on the respective docs pages for the Sky UX 1 and Sky UX 2 modals.

[Blackbaud-PatrickOFriel]

Here's how the ui-bootstrap modal tab behavior works in SKYUX 1, we should probably do something similar: https://github.com/angular-ui/bootstrap/blob/master/src/modal/modal.js#L370

[Blackbaud-PatrickOFriel]

In 2.0.0-rc.8