Examine source code of Fast-Simple Calculator

{
  "name": "Calculator",
  "description": "A simple - fast calculator",
  "homepage_url": "https://github.com/vengeansce/calculator",
  "version": "1.0",
  "manifest_version": 2,
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self';",
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup/index.html",
    "default_title": "Calculator",
    "default_icon": "img/favicon.png"
  },
  "options_ui": {
    "page": "option/index.html",
    "open_in_tab": true,
    "browser_style": false
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Shift+X"
      }
    }
  },
  "icons": {
    "16": "img/favicon-16x16.png",
    "32": "img/favicon-32x32.png",
    "48": "img/favicon-48x48.png",
    "128": "img/favicon-128x128.png"
  },
  "applications": {
    "gecko": {
      "id": "andreasluhut2911@gmail.com"
    }
  }
}