R1:174cf8239802

Provide getObjectOwnerPHID() on inline comment views

Summary:
This returns the PHID of the current revision owner, or the commit author, if one exists.

NOTE: For drafts, we currently return `null`; I'll fix that in a future change. Should be correct for submitted comments.

Test Plan: Added an inline, nothing seemed broken.

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D12185