Touch up PHP/JS interactions for inline comments

Summary:
Ref T1460. Overall:

• Pass objectOwnerPHID consistently.
• Pass viewer consistently.
• Set the correct draft state for checkboxes on the client.

Test Plan:

• Made inline comments in Differential.
• Made inline comments in Diffusion.

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T1460

Differential Revision: https://secure.phabricator.com/D12186