`proxy` causes test errors in Deno

**Update 2023-02-07:** A port for Deno is available at https://deno.land/x/comlink, when the `npm:` protocol is mature enough I will make it compatible with both Node and Deno (and Bun). My intention to merge still holds, let me know, @surma.

**Update:** After some deep dives, I think I can overhaul the proxy mechanism for a clean Deno support. If you want to see this happen, [a coffee would do](https://buymeacoffee.com/vicary). I'll merge everything back when the author is active again.

---

Given this simple worker script,

```ts
// worker.ts
import { expose } from "https://cdn.skypack.dev/comlink?dts";

expose(async function (callback: (...args: unknown[]) => unknown) {
return await callback();
});
```

It runs normally without leaking unclosed MessagePort at runtime via `deno run`:

```ts
// app.ts
import { proxy, wrap } from "https://cdn.skypack.dev/comlink?dts";

const worker = new Worker(new URL("./worker.ts").href, { type: "module" });
const linked = comlink.wrap(worker);
const callback = proxy(() => {
console.log("called.");
});

await linked(callback);

worker.terminate();
```

But when I wrap the code above into a Deno test case `it("should work", async () => { ... });`, the test throws the an error with message `AssertionError: Test case is leaking async ops.`

Full error log (Click to expand)

```bash
error: AssertionError: Test case is leaking async ops.

- 1 async operation to receive a message from a MessagePort was started in this test, but never completed. This is often caused by not awaiting the result of not closing a `MessagePort`. The operation was started here:
at Object.opAsync (deno:core/01_core.js:176:42)
at deno:ext/web/13_message_port.js:143:31
at MessagePort.start (deno:ext/web/13_message_port.js:172:9)
at expose (https://cdn.skypack.dev/-/comlink@v4.3.1-ebLSsXPUzhGrZgtPT5jX/dist=es2019,mode=imports/optimized/comlink.js:111:8)
at Object.serialize (https://cdn.skypack.dev/-/comlink@v4.3.1-ebLSsXPUzhGrZgtPT5jX/dist=es2019,mode=imports/optimized/comlink.js:10:5)
at toWireValue (https://cdn.skypack.dev/-/comlink@v4.3.1-ebLSsXPUzhGrZgtPT5jX/dist=es2019,mode=imports/optimized/comlink.js:222:56)
at Array.map ()
at processArguments (https://cdn.skypack.dev/-/comlink@v4.3.1-ebLSsXPUzhGrZgtPT5jX/dist=es2019,mode=imports/optimized/comlink.js:201:34)
at Object.apply (https://cdn.skypack.dev/-/comlink@v4.3.1-ebLSsXPUzhGrZgtPT5jX/dist=es2019,mode=imports/optimized/comlink.js:178:45)
at Object. (file:///Users/vicary/Documents/Projects/vicary/deno-workerpool/Workerpool.test.ts:146:11)
- 1 async operation to op_host_recv_ctrl was started in this test, but never completed. The operation was started here:
at Object.opAsync (deno:core/01_core.js:176:42)
at hostRecvCtrl (deno:runtime/js/11_workers.js:54:17)
at Worker.#pollControl (deno:runtime/js/11_workers.js:140:36)
at new Worker (deno:runtime/js/11_workers.js:113:24)
at Object. (file:///Users/vicary/Documents/Projects/vicary/deno-workerpool/Workerpool.test.ts:137:20)
at Function.runTest (https://deno.land/std@0.155.0/testing/_test_suite.ts:358:16)
at Function.runTest (https://deno.land/std@0.155.0/testing/_test_suite.ts:346:33)
at fn (https://deno.land/std@0.155.0/testing/_test_suite.ts:316:37)
at testStepSanitizer (deno:runtime/js/40_testing.js:445:13)
at asyncOpSanitizer (deno:runtime/js/40_testing.js:144:15)
- 1 async operation to op_host_recv_message was started in this test, but never completed. The operation was started here:
at Object.opAsync (deno:core/01_core.js:176:42)
at hostRecvMessage (deno:runtime/js/11_workers.js:58:17)
at Worker.#pollMessages (deno:runtime/js/11_workers.js:171:28)

at assert (deno:ext/web/00_infra.js:295:13)
at asyncOpSanitizer (deno:runtime/js/40_testing.js:226:13)
at async resourceSanitizer (deno:runtime/js/40_testing.js:371:7)
at async Object.exitSanitizer [as fn] (deno:runtime/js/40_testing.js:428:9)
at async runTest (deno:runtime/js/40_testing.js:834:7)
at async runTests (deno:runtime/js/40_testing.js:1089:22)
```

I suspect this is caused by a delayed disposal of an opened MessagePort via `proxy` and Deno test doesn't like it, could anyone confirm this?