Examine source code of fastwheel

{
  "manifest_version": 2,
  "name": "fastwheel",
  "description": "A firefox extension that allows users to activate shortcuts using a mouse's scroll wheel.",
  "homepage_url": "https://github.com/hueyjj/fastwheel",
  "version": "0.3resigned1",
  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d20c301b-9991-4b55-8d7d-5da9f788b1f2}"
    }
  }
}