When `worker.terminate()` is called, the spec requires that the
corresponding port message queue is emptied, so no messages can be
received after the call, even if they were sent from the worker before
it was terminated.
The spec doesn't require this of `self.close()`, and since Deno uses
different channels to send messages and to notify that the worker was
closed, messages might still arrive after the worker is known to be
closed, which are currently being dropped. This change fixes that.
The fix involves two parts: one on the JS side and one on the Rust side.
The JS side was using the `#terminated` flag to keep track of whether
the worker is known to be closed, without distinguishing whether further
messages should be dropped or not. This PR changes that flag to an
enum `#state`, which can be one of `"RUNNING"`, `"CLOSED"` or
`"TERMINATED"`.
The Rust side was removing the `WorkerThread` struct from the workers
table when a close control was received, regardless of whether there
were any messages left to read, which made any subsequent calls to
`op_host_recv_message` to return `Ok(None)`, as if there were no more
mesasges. This change instead waits for both a close control and for
the message channel's sender to be closed before the worker thread is
removed from the table.
Classic worker scripts are now executed in the context of a Tokio
runtime. This does mean we can not spawn more tokio runtimes in
"op_worker_sync_fetch". We instead spawn a new thread there, that can
create a new Tokio runtime that we can use to block the worker thread.
