Adding Websocket support to core #19308

The original thread where adding this was discussed #1010 was closed with a decision by the iojs TC to rather implement lower level buffer methods, but that was abandoned.

There is an open EPS to add the feature, but we have since abandoned the process.

Some of the people who originally were -1 changed their opinions in #1010 more recently. In fact, we already ship a partial implementation of ws in the inspector.

I think it might be worth us revisiting adding WS to core.

/cc @eugeneo @rauchg