Item under cursor is re-highlighted when using the keyboard to scroll through items

[CMTegner]

When using the keyboard to scroll items into view the highlighted item will change unexpectedly. It seems as though the item where the cursor is resting is re-highlighted when the offset of the list is changed (to bring the offscreen item you want to highlight into view).

I was able to reproduce this in Chrome, Firefox, and Safari, all on macOS Sierra (didn't try any other browsers).