The Web Developer Extension for Firefox and Mozilla has been updated to v0.9.3. This update adds update notification, fixes several bugs, and improves localization. The release notes are available here.
According to the developer, “Mozilla Update is no longer accepting updates to it’s list of extensions, but the latest version of the Web Developer extension is always available at chrispederick.com. The version of the extension supports the latest releases of Mozilla Firefox and Mozilla, and includes update notification support for Mozilla Firefox.”