This reverts commit 4ef5e31.
Firebug must be activated on at least one tab once before this will exist. Fixes #1540
Side effect: reverted the "update URL must be secure" commit. We need to not have that for this to work, and in thinking about this I realized that isn't necessary. (Even if you can fake the update check, the actual update's download still needs to be secure.) Also: Refactored updateURL so the patching logic is in the getter, thus always applied regardless of order of operations.
This reverts commit 7cefe18.