XS WeakMap memory leak

test-wm-gc.js

if (typeof console === "undefined") {
  globalThis.console = {
    log() {
      print(...arguments);
    },
  };
}

let queueGCJob;
if (typeof setTimeout === "function") {
  queueGCJob = function() {
    return new Promise(function(resolve) {
      setTimeout(resolve, 0);
    });
  };
} else if (typeof drainJobQueue === "function") {
  queueGCJob = function() {
    return new Promise(function(resolve) {
      drainJobQueue();
      resolve();
    });
  };
} else {
  queueGCJob = function() {
    return Promise.resolve();
  };
}

let gc;

const setupGC = async () => {
  gc = globalThis.gc || (typeof $262 !== "undefined" ? $262.gc : null);
  if (!gc) {
    try {
      const [{ ["default"]: v8 }, { ["default"]: vm }] = await Promise.all([
        import("v8"),
        import("vm"),
      ]);
      v8.setFlagsFromString("--expose_gc");
      gc = vm.runInNewContext("gc");
      v8.setFlagsFromString("--no-expose_gc");
    } catch (err) {
      gc = () => void Array.from({ length: 2 ** 24 }, () => Math.random());
    }
  }
  globalThis.gc = gc;
};

// Hold map inside of key to make sure key is visited first by mark
const key = { map: new WeakMap() };
let refValue;
let refSentinel;

setupGC()
  .then(() => {
    const value = {};
    const sentinel = {};
    refValue = new WeakRef(value);
    refSentinel = new WeakRef(sentinel);
    key.map.set(key, value);
    key.map.delete(key);
  })
  .then(async () => {
    await queueGCJob();
    gc();
  })
  .then(() => {
    // Keep a reference to key throughout
    void key;
    console.log(!!refSentinel.deref(), !!refValue.deref());
  });