Summary: Ref T7689, which discusses some of the motivation here. Briefly, these methods are awkward: - Controller->loadHandles() - Controller->loadViewerHandles() - Controller->renderHandlesForPHIDs() This moves us toward better semantics, less awkwardness, and a more reasonable attack on T7688 which won't double-fetch a bunch of data. Test Plan: - Added unit tests. - Converted one controller to the new stuff. - Viewed countdown lists, saw handles render. Reviewers: btrahan Reviewed By: btrahan Subscribers: epriestley Maniphest Tasks: T7689 Differential Revision: https://secure.phabricator.com/D12202