If there's an update in progress, resolve with the update's promise. Part of #180
If there's an update in progress, resolve with the update's promise. Part of #180

karolklp/ServiceWorker,martinthomson/ServiceWorker,slightlyoff/ServiceWorker,zuzusik/ServiceWorker,zuzusik/ServiceWorker,justinleoye/ServiceWorker,chadoliver/ServiceWorker,karolklp/ServiceWorker,slightlyoff/ServiceWorker,justinleoye/ServiceWorker,justinleoye/ServiceWorker,karolklp/ServiceWorker,chadoliver/ServiceWorker,martinthomson/ServiceWorker,zuzusik/ServiceWorker,martinthomson/ServiceWorker,mkruisselbrink/ServiceWorker,chadoliver/ServiceWorker,mkruisselbrink/ServiceWorker