Do not broadcast storage events if storage is already empty

[shannonbooth]

This is already implemented by browsers, and tested by WPT under: webstorage/event_no_duplicates.html

• At least two implementers are interested (and none opposed):
  • …
  • …
• Tests are written and can be reviewed and commented upon at:
  • https://github.com/web-platform-tests/wpt/blob/3bddeaf2bd7cda236fb3ffbe743a50f363b03fa2/webstorage/event_no_duplicates.html#L98
• Implementation bugs are filed:
  • Chromium: Already implemented
  • Gecko: Already implemented
  • WebKit: Already implemented
  • Deno: N/A (I think? Don't think StorageEvent would apply)
  • Node.js: N/A
• Corresponding HTML AAM & ARIA in HTML issues & PRs: N/A
• MDN issue is filed: N/A
• The top of this comment includes a clear commit message to use.

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

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/acknowledgements.html ( diff )
/webstorage.html ( diff )