Set up colspec for differential 1up

Summary: This upgrades 1up view from "does not work" back to "barely works".

Test Plan: view diff, 1up and 2up.

Reviewers: Blessed Reviewers, epriestley

Reviewed By: Blessed Reviewers, epriestley

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D10854