This change moves the `crypto()` getter from `Window` to
`WorkerOrWindowGlobalScope`. This aligns our implementation with the
WebCrypto specification.
(cherry picked from commit 89b6cd3fb1b9a3058dbada9e12606950b466936a)
This aligns Workers and Window and MessagePorts to all use the same
mechanism for transferring serialized messages across realms.
It also allows transferring more message ports into a worker.
Re-enable the Worker-echo test, as none of the MessagePort tests have
themselves been flaky, and those are now using the same underlying
implementation.
