[1] Service Workers Nightly (2017-02-16 20:10:49 +09:00) https://w3c.github.io/ServiceWorker/#service-worker-registration-navigationpreloadmanager

[2] Speed up Service Worker with Navigation Preloads | Web | Google Developers (2017-02-18 00:09:13 +09:00) https://developers.google.com/web/updates/2017/02/navigation-preload