Summary:
This currently uses a hard-coded relative path, but should not, especially after D9401.
The major effect of this is that updated .swf files might not be served properly, and we were at the whims of the server configuration for caching/versioning behavior.
Test Plan: Enabled debug notifications, saw .swf load through Celerity.
Reviewers: joshuaspence
Reviewed By: joshuaspence
Subscribers: epriestley
Differential Revision: https://secure.phabricator.com/D9421