Summary: Ref T7538. We can figure out whether to backport this to main Conpherence later and/or remove buttons, etc., but this behavior seems pretty clearly good.
Test Plan:
- Pressed enter (sent message).
- Pressed shift+enter (newline).
Reviewers: btrahan, chad
Reviewed By: chad
Subscribers: epriestley
Maniphest Tasks: T7538
Differential Revision: https://secure.phabricator.com/D12085
e6f1c34a47