The link tag with rel=serviceworker behaviour here is part of 'Foreign-Fetch' - an experiment too allow third-parties to install a serviceworker e.g. analytics

The link tag with rel=serviceworker behaviour here is part of 'Foreign-Fetch' - an experiment too allow third-parties to install a serviceworker e.g. analytics provider could install a SW that handles analytics offline so a developer doesn't need to. I think the origin-trial for this expires early next year. https://developers.google.com/web/updates/2016/09/foreign-fetch https://developers.google.com/web/updates/2016/09/foreign-fe... https://groups.google.com/a/chromium.org/forum/#!topic/Blink-dev/sIzHpZVhmBE https://groups.google.com/a/chromium.org/forum/#!topic/Blink...