Correct note from within `serviceworker.js`
Merge pull request #1337 from alrra/correct-notes

Correct note from within `serviceworker.js`
Add test for the `Beacon API`

W3C Specification:
https://dvcs.w3.org/hg/webperf/raw-file/tip/specs/Beacon/Overview.html
Merge pull request #1339 from alrra/beacon

Add test for the `Beacon API`