Fix a Quicksand/Lightbox contention issue

Summary:
Fixes T11785. Lightbox calls JX.Stratcom.pass() to let other handlers react, but should not. At least today, we never put, e.g., links inside a lightbox.

This code appears in the original commit so it was probably just copy/pasted from somewhere and I missed it in review.

(Or there's some edge case I'm not thinking of and we'll figure it out soon enough.)

Additionally, blacklist /file/data/ from Quicksand naviagtion: Quicksand should never fetch these URIs.

Test Plan:

• Disabled security.alternate-file-domain.
• Enabled Quicksand ("Persistent Chat").
• Clicked an image thumbnail on a task.
  • Repeated that until things flipped out a bit.
  • After the patch: no issues.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11785

Differential Revision: https://secure.phabricator.com/D16884