Ref T11114. This is a transitional change that breaks a bunch of stuff. I'll hold it until I've restored features.

This stuff works:

• Commenting.
• Subscribers/tags/reviewers.
• Pinning.
• Drafts.

This stuff does not work yet:

• Preview of inline comments.
• Probably submitting inlines, whatsoever.
• Comment-area warnings like "There are failing tests."
• All meaningful actions (accept, reject, etc).

Commented on a revision. Essentially nothing else works yet.