Add `ev.ports` for spec compliancy.
Since we only emit the raw `data` value, and only create the
`MessageEvent` instance if there are EventTarget-style listeners,
we store the ports list temporarily on the MessagePort object itself,
so that we can look it up when we need to create the event object.
Fixes: https://github.com/nodejs/node/issues/37358
PR-URL: https://github.com/nodejs/node/pull/37538
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
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