MAIN-939: fix chopped off dropdowns on wall/forum pages.

https://wikia-inc.atlassian.net/browse/MAIN-939

This is a good quick fix for the problem mentioned in the ticket, however, it's not very elegant and has caveats (see code comments). I'm hesitant to remove the overflow on the article area because, IMO, content within it should be controlled properly (aside from handling wide tables, it also controls huge images and long unbreaking lines of text properly).

There may be some other solutions to this in the long term if we find other cases of elements getting chopped off which should be explored if this becomes a bigger issue.