Examine source code of showModalDialog Shim

{
  "manifest_version": 2,
  "name": "showModalDialog Shim",
  "version": "1.1resigned1",
  "description": "showModalDialog shim",
  "icons": {
    "48": "ico.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.cloudexchange.fr/*",
        "*://*.cloudexchange.fr/*"
      ],
      "js": [
        "shim.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b02e593b-2c95-4607-8033-a9371dad4ec3}"
    }
  }
}