Also push the onconnect event for the initial connection.
This still doesn't properly handle sending an onconnect event to a
pre-existing SharedWorkerGlobalScope with the same name for the same
origin, but it does give us a lot of WPT passes in the SharedWorker
category.
Instead of wrapping all non-movable members of TransportSocket in OwnPtr
to keep it movable, make TransportSocket itself non-movable and wrap it
in OwnPtr.
This has been a longstanding ergonomic issue with our IPC compiler. Non-
trivial types were previously passed by const&. So if we wanted to avoid
expensive copies, we would have to const_cast and move the data.
We now pass ownership of all transferred data to the client subclasses.
This allows us to remove const_cast from these methods, and allows us to
avoid some trivial expensive copies that we didn't bother to const_cast.
