When opening https://www.webrtc-experiment.com/Pluginfree-Screen-Sharing it will fail to start screen sharing (2nd issue)

When opening https://www.webrtc-experiment.com/Pluginfree-Screen-Sharing in simplebrowser it will fail with

NotAllowedError: Invalid state

when trying to start screen sharing. As this is a plugin free approach using WebRTC then it should be working fine.

Steps to reproduce:

1. Build & start simplebrowser sample project
2. Navigate to https://www.webrtc-experiment.com/Pluginfree-Screen-Sharing
3. Press the "Share Your Screen" button
4. Observe "NotAllowedError: Invalid state" error displayed in the webpage

I've also experienced occasional crashes while testing this, but have not been able to deterministically reproduce them.