Summary: `$engine` will be undefined here. This was just copy/paste derp, combined with me accidentally having an `.arclint` file in a place I didn't expect to have one when I tried to test this.
Test Plan: Ran `arc linters` in a totally bare, non-.arclint-having working copy
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Differential Revision: https://secure.phabricator.com/D9255