webextensions/manifest/developer.json

{
  "webextensions": {
    "manifest": {
      "developer": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/manifest.json/developer",
          "support": {
            "chrome": {
              "version_added": false
            },
            "edge": "mirror",
            "firefox": {
              "version_added": "52"
            },
            "firefox_android": "mirror",
            "opera": {
              "version_added": "≤45"
            },
            "safari": {
              "version_added": false
            },
            "safari_ios": "mirror"
          }
        }
      }
    }
  }
}