FF155 ExprFeat: buffer boundary assertions in regexp

[hamishwillee]

FF153 supports buffer boundary assertions in Regexp (in Nightly and behind a pref) in https://bugzilla.mozilla.org/show_bug.cgi?id=2047706

This adds experimental features and relnote updates.

Related docs work can be tracked in #45183

[github-actions]

Preview URLs (1 page)

• /en-US/docs/Mozilla/Firefox/Experimental_features

Flaws (1)

Found an unexpected or unresolvable flaw? Please report it here.

URL: /en-US/docs/Mozilla/Firefox/Experimental_features
Title: Experimental features in Firefox
Flaw count: 1

• broken_links:
  • Link /en-US/docs/Web/JavaScript/Reference/Regular_expressions/Buffer_boundary_assertion doesn't resolve

External URLs (1)

URL: /en-US/docs/Mozilla/Firefox/Experimental_features
Title: Experimental features in Firefox

• https://bugzil.la/2047706 (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2026-08-27 23:45:28)

[dipikabh]

Thanks @hamishwillee!

• files/en-us/mozilla/firefox/experimental_features/index.md looks good, just one nit
• You can drop the files/en-us/mozilla/firefox/releases/155/index.md change - I've ported your note as an update suggestion to #45270

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[hamishwillee]

Thanks @dipikabh - done!