lib: allow Writeable.toWeb() to work on http.Outgoing message

Attempted to fix the issue by watering down the condition being
checked in internal/streams/utils isWritableNodeStream utility

Fixes: #44188
PR-URL: #45642
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>

lib/internal/webstreams/adapters.js

@@ -101,11 +101,17 @@ function newWritableStreamFromStreamWritable(streamWritable) {
   // here because it will return false if streamWritable is a Duplex
   // whose writable option is false. For a Duplex that is not writable,
   // we want it to pass this check but return a closed WritableStream.
-  if (typeof streamWritable?._writableState !== 'object') {
+  // We check if the given stream is a stream.Writable or http.OutgoingMessage
+  const checkIfWritableOrOutgoingMessage =
+    streamWritable &&
+    typeof streamWritable?.write === 'function' &&
+    typeof streamWritable?.on === 'function';
+  if (!checkIfWritableOrOutgoingMessage) {
     throw new ERR_INVALID_ARG_TYPE(
       'streamWritable',
       'stream.Writable',
-      streamWritable);
+      streamWritable
+    );
   }
 
   if (isDestroyed(streamWritable) || !isWritable(streamWritable)) {

test/parallel/test-stream-toWeb-allows-server-response.js

@@ -0,0 +1,29 @@
+'use strict';
+const common = require('../common');
+const { Writable } = require('stream');
+
+const assert = require('assert');
+const http = require('http');
+
+// Check if Writable.toWeb works on the response object after creating a server.
+const server = http.createServer(
+  common.mustCall((req, res) => {
+    const webStreamResponse = Writable.toWeb(res);
+    assert.strictEqual(webStreamResponse instanceof WritableStream, true);
+    res.end();
+  })
+);
+
+server.listen(
+  0,
+  common.mustCall(() => {
+    http.get(
+      {
+        port: server.address().port,
+      },
+      common.mustCall(() => {
+        server.close();
+      })
+    );
+  })
+);