List refactoring: remove the scrolling container, fix #270
Remove all scrollableNode and d-list-container references
Remove position:relative on List (see discussion)
List.css cleanup (overflow-x, ...)
Fix selected item persistance when focusing/unfocusing
Remove a functional test that was not correct
Add Sauce keys

(cherry picked from commit 27b23fd19de27f51d60b0549d44894c5a97bdaa8)