URLSearchParams has been implemented and will be included in an upcoming Windows 10 Insider Preview Build.Jake Archibald commented
This may become a prerequisite for service workers. They're really useful there, and it wouldn't surprise me if it was used in the wild.
Service Worker was turned on by default in Edge included in Windows 10 Insider Preview Build 17063.Jake Archibald commented
"background-fetch monopolized proceedings" - lol it wasn't discussed at all.
This work is now in Microsoft Edge Insiders Preview 17074 and higher.