Dropdown v2 doesn't scroll when navigating with keyboard

[sid-6581]

I'm submitting a ...

[x] bug report
[ ] feature request
[ ] support request

For the dropdown control in 2.5.1, if there is a scroll bar, navigating up and down with the keyboard will not scroll the contents. The item is selected, but the mouse has to be used for scrolling. This can be seen in the showcase for 2.5.1 in the dropdown with filtering, where there are too many countries to fit. Start scrolling with the keyboard and you'll see the items selected as you go down, but they are not scrolled into view.