webextension-polyfill updates

[rebloor]

Description

These changes are designed to emphasize that the webextension-polyfill is now only needed when an extension want to target Chrome 147 or earlier.

Related issues and pull requests

Related changes to the Extension Workshop content in mozilla/extension-workshop#2401.
Fixes #44114 (with content from Issue-44114-Chrome-support-for-the-browser-namespace)

[github-actions]

Preview URLs (5 pages)

• /en-US/docs/Mozilla/Add-ons/WebExtensions/API/proxy
• /en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/executeScript
• /en-US/docs/Mozilla/Add-ons/WebExtensions/API
• /en-US/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension
• /en-US/docs/Mozilla/Add-ons/WebExtensions/Differences_between_API_implementations

External URLs (10)

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API
Title: JavaScript APIs

• https://crbug.com/500769389 (1 time) (Note! This may be a new URL 👀)
• https://github.com/mozilla/webextension-polyfill (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API/proxy
Title: proxy

• https://developer.chrome.com/docs/extensions/reference/api/proxy (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/executeScript
Title: tabs.executeScript()

• https://github.com/mozilla/webextension-polyfill (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension
Title: Build a cross-browser extension

• https://crbug.com/500769389 (2 times) (Note! This may be a new URL 👀)
• https://developer.chrome.com/docs/extensions/develop/concepts/browser-namespace (1 time) (Note! This may be a new URL 👀)
• https://developer.chrome.com/docs/extensions/develop/migrate (2 times) (Note! This may be a new URL 👀)
• https://extensionworkshop.com/documentation/develop/manifest-v3-migration-guide/ (1 time) (Note! This may be a new URL 👀)
• https://github.com/mozilla/webextension-polyfill/ (2 times) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/Differences_between_API_implementations
Title: Differences between API implementations

• https://developer.chrome.com/docs/extensions/develop/migrate (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2026-08-09 19:14:17)

[Rob--W]

Could you update the text to account for mozilla/webextension-polyfill#942 ? There is a small subset of extensions where "148" does not apply, but "152" does.

[rebloor]

@Rob--W updated re 152

[Rob--W]

I think that this might be conflicting with some other PRs, notably #44959 and the older PR at #44149 . In the interest of avoiding duplicate/overlapping work I suggest combining 44149 with this one (this one about 152+148 supersedes the part about 148).

I already approved Oliver's PR, so we could also merge that first, merge/rebase this branch. And then do a final pass for inconsistencies. I spotted at least one inconsistency, the existing claim that devtools doesn't support Promise. That note should be adjusted to state that support was added in 152.

[github-actions]

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

[github-actions]

[mdn-linter] _{reported by reviewdog 🐶}

Suggested change

[rebloor]

@Rob--W includes changes from #44149, and I've made updates, so everything should now be accurate and consistent. I'm wondering whether, when we can be reasonably assured that most new cross-browser development will target the versions supporting the browser and promises, we should review the three articles to eliminate any confusion or uncertainty about which one to consult.