UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. Enable Offline mode in DevTools
2. Call .scheduleSync('foo')
3. In SW, log calls to self.addEventListener('sync')

What is the expected behavior?
Expected behavior is for the sync event to not be called until the browser is online.

What went wrong?
Sync event is fired almost immediately.

Did this work before? N/A 

Chrome version: 56.0.2924.87  Channel: stable
OS Version: 10.0
Flash Version: 

This issue feels very similar to this one: https://bugs.chromium.org/p/chromium/issues/detail?id=422956

If I physically remove my machine from the network (really offline, instead of offline emulated), then the behavior works as expected.