Examine source code of HN Collapse

{
  "manifest_version": 2,
  "name": "HN Collapse",
  "version": "1.2resigned1",
  "description": "Makes hacker news comments collapsible.",
  "icons": {
    "48": "icons/collapse-48.png"
  },
  "applications": {
    "gecko": {
      "id": "hn-collapse@mozilla.org",
      "strict_min_version": "45.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://news.ycombinator.com/item?*"
      ],
      "js": [
        "collapse.js"
      ],
      "css": [
        "collapse.css"
      ]
    }
  ]
}