Diffusion - fix browse file bug

Summary: we were calling a member method on a diffusion hash. not sure why.  Fixes T4402

Test Plan: clicked about, no fatals and seemed to move sensical backwards in time

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T4402

Differential Revision: https://secure.phabricator.com/D8194