Delete unused configuration variable

Summary: This was suggested in D2625#2 and is a competition for D2625.

Test Plan: Viewed wide and non-wide diff in Firefox, Chrome, IE.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin, ReturnZero

Differential Revision: https://secure.phabricator.com/D2652