R1:c058bbd45514

Tweak padding on revision history table.

Summary: Added 6px to the left and right of each TD on the revision history table.

Test Plan: Used Chrome and a table with many revisions.

Reviewers: vrana, epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4197