Fix GNOME shell error message about factsBox.FactsBox
Created by: mwilck
Fixes this error message:
gnome-shell[13339]: Some code accessed the property 'FactsBox' on the module 'factsBox'. That property was defined with 'let' or 'const' inside the module. This was previously supported, but is not correct according to the ES6 standard. Any symbols to be exported from a module must be defined with 'var'. The property access will work as previously for the time being, but please fix your code anyway.
This re-applies 36b07b46 ("Fix GNOME shell error message about factsBox.FactsBox"), which seems to have been mistakenly removed by the merge commit 801dddd4.