Describe your issue or idea

SmartMenus is in core and provides the front-end drop-down menus in the menu blocks. We should use it for Admin Bar as well to solve accessibility issues as well as some other existing problems:

520 | [UX] admin bar search results should not be allowed to span further than the page height.

2172 | Dropdown menus: when the menu is longer than the viewport and you scroll, menu items get blurry (only on Chrome)

2161 | [UX] Drop-down menus: 1st item in long menus is hidden under the admin bar.

4549 | [UX] Admin Bar drop-downs go off-screen

All of the above problems may be solved by using SmartMenus instead of custom JavaScript included in Admin Bar.

GitHub Issue #: