Pass "object" to modular transaction methods explicitly
Ref T13682. When editing a comment, the edit pathway may invoke file PHID extraction without first formalizing an object on the Editor.
Pass the "object" explicitly to generally improve the robustness of this pathway.
Test Plan: Edited a comment.
Maniphest Tasks: T13682
Differential Revision: https://secure.phabricator.com/D21839