HTTP is insecure Firefox

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manifest.json
{
  "manifest_version": 2,
  "name": "HTTP says insecure",
  "version": "1.1resigned1",
  "description": "Extension that makes the browser red when browsing a http site",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "theme",
    "tabs"
  ],
  "applications": {
    "gecko": {
      "id": "insecure@http",
      "strict_min_version": "60.0"
    }
  },
  "icons": {
    "48": "./icon.png"
  }
}

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