worker: export workerData to ESM workers

lib/worker_threads.js

@@ -17,5 +17,6 @@ module.exports = {
   MessageChannel,
   threadId,
   Worker,
-  parentPort: null
+  parentPort: null,
+  workerData: null,
 };

test/fixtures/worker-data.mjs

@@ -0,0 +1,3 @@
+import { workerData, parentPort } from 'worker_threads';
+
+parentPort.postMessage(workerData);

test/parallel/test-worker-mjs-workerdata.js

@@ -0,0 +1,16 @@
+'use strict';
+const common = require('../common');
+const fixtures = require('../common/fixtures');
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+
+const workerData = 'Hello from main thread';
+
+const worker = new Worker(fixtures.path('worker-data.mjs'), {
+  workerData,
+  execArgv: ['--experimental-modules']
+});
+
+worker.on('message', common.mustCall((message) => {
+  assert.strictEqual(message, workerData);
+}));