R1:9dacf39cf1b2

Pass target diff to revision detail renderer

Summary: We need to use commit diff in some links and manual diff in some others.

Test Plan: Displayed revision, verified that the action link uses commit diff.

Reviewers: epriestley, nh

Reviewed By: nh

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3300