UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/64.0.3282.167 Chrome/64.0.3282.167 Safari/537.36

Steps to reproduce the problem:
1. Visit https://www.websocket.org/echo.html
2. Establish connection
3. Open up DevTools and set Network Conditions to "Offline"
4. Click "Send" button

What is the expected behavior?
Throttling / setting Network Conditions to offline should also affect WebSocket connections.

What went wrong?
Throttling / Setting conditions to "Offline" did not affect open WebSockets connection(s)

Did this work before? N/A 

Chrome version: 64.0.3282.167  Channel: stable
OS Version: Ubuntu 16.04.4 LTS
Flash Version: