Update OOjs UI to v0.1.0-pre (15f4156bac)

New changes:
15f4156 Follow-up 2334482: actually clear items in clearItems()

Change-Id: I7d4570364690b82a6fb7de3beb7e7e68ff451366
Merge "Update OOjs UI to v0.1.0-pre (15f4156bac)"