Firefox 6 added ::-moz-progress-bar CSS pseudo-element (#27195)

Co-authored-by: Claas Augner <[email protected]>

Author: queengooborg

css/selectors/-moz-progress-bar.json

@@ -12,7 +12,7 @@
             "chrome_android": "mirror",
             "edge": "mirror",
             "firefox": {
-              "version_added": "≤72"
+              "version_added": "6"
             },
             "firefox_android": "mirror",
             "oculus": "mirror",