JavaScript ShadowRealm proposal integration

[Ms2ger]

To replace #5339.

• At least two implementers are interested (and none opposed):
  • ShadowRealm API mozilla/standards-positions#997
  • …
• [·] Tests are written and can be reviewed and commented upon at:
  • In progress across multiple pull requests; see https://github.com/web-platform-tests/wpt/pulls?q=is%3Apr+is%3Aopen+shadowrealm
• Implementation bugs are filed:
  • Chromium: https://issues.chromium.org/issues/41480387
  • Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1797187
  • WebKit: https://bugs.webkit.org/show_bug.cgi?id=283289
  • Deno (only for timers, structured clone, base64 utils, channel messaging, module resolution, web workers, and web storage): [WIP] Implement the ShadowRealm constructor denoland/deno#16211
  • Node.js (only for timers, structured clone, base64 utils, channel messaging, and module resolution): …
• MDN issue is filed: Document ShadowRealm mdn/content#36842
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

TODO:

• Prepare PRs for dependent specs to adjust to terminology changes

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/browsing-the-web.html ( diff )
/dom.html ( diff )
/embedded-content.html ( diff )
/form-elements.html ( diff )
/index.html ( diff )
/infrastructure.html ( diff )
/media.html ( diff )
/nav-history-apis.html ( diff )
/references.html ( diff )
/scripting.html ( diff )
/structured-data.html ( diff )
/timers-and-user-prompts.html ( diff )
/webappapis.html ( diff )
/workers.html ( diff )