Fix appearance of article icon


Fix appearance of article icon

This icon only appears in non-JS mode, on the "Load more"
button. It wasn't showing because we weren't loading the
OOUI icon pack that contains it. It should also be inverted
(white instead of black) because it's being used on a
blue background.

Depends on Iac0e612f in OOUI to make the inverted icon available.

Bug: T102908
Change-Id: I689edccf5271c91442e651b726b30a86f7ffe6c4