refactor: clean up "Drilldown._hideAll()" method
refactor: clean up "Drilldown._hideAll()" method

1. Retrieve datas and elements
2. Apply actions on them
3. Trigger events

abdullahsalem/foundation-sites,DaSchTour/foundation-sites,zurb/foundation-sites,denisahac/foundation-sites,denisahac/foundation-sites,zurb/foundation,abdullahsalem/foundation-sites,zurb/foundation,zurb/foundation-sites,denisahac/foundation-sites,zurb/foundation-sites,zurb/foundation,DaSchTour/foundation-sites,abdullahsalem/foundation-sites