worker: add Symbol.toStringTag to messaging classes

[lazerg]

MessageChannel, MessagePort and BroadcastChannel had no
Symbol.toStringTag, so Object.prototype.toString.call() returned
[object Object] or [object EventTarget] rather than the interface
names.

Two existing tests expected util.inspect() to print
MessagePort [EventTarget]; the tag now matches the constructor name,
so the bracketed part is gone.

Fixes: #65527

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.65%. Comparing base (4b5e86c) to head (070a5ec).
⚠️ Report is 690 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65532      +/-   ##
==========================================
+ Coverage   90.14%   91.65%   +1.51%     
==========================================
  Files         751      789      +38     
  Lines      253679   285455   +31776     
  Branches    47789    69104   +21315     
==========================================
+ Hits       228671   261635   +32964     
+ Misses      16264    14430    -1834     
- Partials     8744     9390     +646     

Files with missing lines	Coverage Δ
lib/internal/worker/io.js	99.23% <100.00%> (+0.03%)	⬆️

... and 283 files with indirect coverage changes

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[brettz9]

Could the failure be flake, remedied by another test run?

[lazerg]

The failure does not come from this change. wpt/test-web-locks crashed on macOS after all of its subtests passed. That matches the known flake in #59142, where held.https.any.js throws an expected rejection and the harness does not register it. test/wpt/status/web-locks.json already marks that file flaky, and its note covers ppc, linux x64 and s390x only. The same commit passed test-linux on both arches, which runs the same WPT suite, and my diff only defines Symbol.toStringTag on the three messaging classes. A new run should come back green, but I cannot start one here.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/77919/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/77957/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/77976/

[nodejs-github-bot]

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✔  Done loading data for nodejs/node/pull/65532
----------------------------------- PR info ------------------------------------
Title      worker: add Symbol.toStringTag to messaging classes (#65532)
Author     Lazizbek Ergashev <lazerg2@gmail.com> (@lazerg)
Branch     lazerg:fix/issue-65527-messageport-tostringtag -> nodejs:main
Labels     author ready, worker, needs-ci, commit-queue
Commits    2
 - worker: add Symbol.toStringTag to MessageChannel and MessagePort
 - worker: add Symbol.toStringTag to BroadcastChannel
Committers 1
 - Lazizbek Ergashev <lazerg2@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/65532
Fixes: https://github.com/nodejs/node/issues/65527
Reviewed-By: James M Snell <jasnell@gmail.com>
------------------------------ Generated metadata ------------------------------
PR-URL: https://github.com/nodejs/node/pull/65532
Fixes: https://github.com/nodejs/node/issues/65527
Reviewed-By: James M Snell <jasnell@gmail.com>
--------------------------------------------------------------------------------
   ℹ  This PR was created on Tue, 25 Aug 2026 08:10:52 GMT
   ✔  Approvals: 1
   ✔  - James M Snell (@jasnell) (TSC): https://github.com/nodejs/node/pull/65532#pullrequestreview-5018748441
   ✖  1 GitHub CI job(s) failed:
   ✖    - test-macOS: FAILURE (https://github.com/nodejs/node/actions/runs/32835191997/job/97762371901)
   ℹ  Last Full PR CI on 2026-09-26T20:19:31Z: https://ci.nodejs.org/job/node-test-pull-request/77976/
�[36m⠙�[39m Querying data for job/node-test-pull-request/77976/
�[36m⠙�[39m Querying data for job/node-test-pull-request/77976/
�[36m⠙�[39m Querying API for job/node-test-pull-request/77976/
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   ✔  Last Jenkins CI successful
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   ✔  Aborted `git node land` session in /home/runner/work/node/node/.ncu

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[panva]

Landed in 7ff6267...cd908df