Spider/Crawler Google Favicon not detected as  Spider

Google Favicon is the user agent for downloading favicons defined by websites. 
https://developers.google.com/search/docs/advanced/appearance/favicon-in-search#crawler

```text
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko)  Chrome/49.0.2623.75 Safari/537.36 Google Favicon
```