WebSocket: Enable WSS support by default.

[kristijanburnik]

This PR should enable support for using WebSockets over SSL.

This feature also depends on the wpt-tools WSS support:
https://github.com/w3c/wpt-tools/pull/8/files

@jgraham, @foolip, @mikewest

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[mikewest]

I'm not at all familiar with websockets' tests, but this patch makes sense to me. Still, I'll defer to @jgraham, et al on this.