WebSocket invalid server does not invoke onerror reliably

[ryantrem]

Describe the bug
Based on unit tests, it seems that WebSocket is not calling the onerror callback reliably for invalid servers.

To Reproduce
Steps to reproduce the behavior:

1. Run the "should trigger error callback with invalid server" unit test repeatedly (NOTE: This test was commented out in Flesh out URL polyfill and add performance.now polyfill #130).
2. Observe that regardless of how long the timeout is, the test will fail about 1/3 of the time.

Expected behavior
onerror should be called reliably.

Other

• This may only happen with Chakra, but I'm not sure.