Fix weird "0" notification numbers

Summary: The JsShrink change swapped an "== 0" for "=== 0" in JS, but we're currently sending a string down. Fixes T3230.

Test Plan: I'm not 100% sure this actually fixes it but probably? Let me know if you still see it.

Reviewers: chad, btrahan

Reviewed By: chad

CC: aran

Maniphest Tasks: T3230

Differential Revision: https://secure.phabricator.com/D5997