lib: remove var as performance boost no longer apply
The performance improvement previous from V8 TDZ should no longer apply here anymore. Therefore I think we can safely move to let and remove the linting rule.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
The performance improvement previous from V8 TDZ should no longer apply here anymore. Therefore I think we can safely move to let and remove the linting rule.