WebSocket tests failing in Sauce Labs

[jugglinmike]

Many WebSocket tests are producing TIMEOUT errors in Sauce-Labs-mediated browsers

https://wpt.fyi/results/websockets?sha=1dc612f2ed

This appears to affect any test that depends on WebSocket traffic rather than synchronous behavior. That suggests a problem with the communication channel between the workers and Sauce Labs.

[jugglinmike]

Sauce Labs uses SSL bumping by default, and that interferes with WebSocket traffic. We initially resolved the problem by disabling SSL bumping, but because WPT uses a self-signed certificate, that had the unfortunate side effect of interfering with HTTPS traffic.

We re-enabled SSL bumping via gh-636, so this is once again an issue. Here's what I'm thinking for a new solution:

• Configure the Sauce Labs virtual machine to accept WPT's self-signed certificate via the "pre-run executable" for Windows
• Disable SSL bumping once again

That first step may not be possible, so ideas for alternative approaches are more than welcome!