UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36

Steps to reproduce the problem:
1. Create a simple web-server that sets a cookie -- nodejs reference below:

```
var http = require('http');

http.createServer(function (request, response) {
  // To Write a Cookie
  response.writeHead(200, {
    'Set-Cookie': 'mycookie=test; domain=ngrok.io',
    'Content-Type': 'text/plain'
  });
  response.end('Hello World\n');
}).listen(8124, console.log.bind(console, 'server started'));
```

2. Launch an ngrok tunnel to :8124, visit that tunnel
3. Note in page info or devtools > app storage that the cookie is not set. Also note, that if you set the cookie for the fully qualified domain it works. Finally, if you use a different domain, everything works as well.

What is the expected behavior?
Chrome should honor set-cookie for ngrok.io subdomains. 

What went wrong?
The browser does not store the cookie for any ngrok subdomain if the cookie domain is set to ngrok.io.

Did this work before? No 

Does this work in other browsers? Yes

Chrome version: 60.0.3112.113  Channel: n/a
OS Version: OS X 10.12.5
Flash Version: 

No