title: Credentials: 'include' not including Cookie header
body: <p>I'm using <code>credentials: 'include'</code> and <code>mode: 'cors'</code> on the client. On the server I see <code>access-control-allow-credentials: true</code> and <code>access-control-allow-origin: https://dev.com:9443</code> headers. I don't see my <code>cookie</code> header though and I can't seem to find why it isn't sending. Let me know if I can provide any further details.</p>
  
  <p>Fetch request</p>
  
  <pre class="lang-js prettyprint-override"><code>fetch(url, {
    method: 'get',
    credentials: 'include',
    mode: 'cors',
    headers: {
      'Content-Type': 'application/json'
    }
  });
  
  </code></pre>
  
  <p>Options Request Headers</p>
  
  <pre><code>:authority: prod.fakedomain.com
  :method: OPTIONS
  :path: /Search
  :scheme: https
  accept: */*
  accept-encoding: gzip, deflate, br
  accept-language: en-US,en;q=0.9,fr;q=0.8,la;q=0.7
  access-control-request-headers: content-type
  access-control-request-method: GET
  cache-control: no-cache
  dnt: 1
  origin: https://dev.com:9443
  pragma: no-cache
  referer: https://dev.com:9443/
  user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36
  </code></pre>
  
  <p>Options Response Headers</p>
  
  <pre><code>access-control-allow-credentials: true
  access-control-allow-headers: content-type
  access-control-allow-methods: GET,HEAD,POST
  access-control-allow-origin: https://dev.com:9443
  access-control-max-age: 1800
  allow: GET, HEAD, POST, PUT, DELETE, TRACE, OPTIONS, PATCH
  content-length: 0
  date: Mon, 04 Feb 2019 03:45:06 GMT
  status: 200
  vary: Origin
  x-application-context: application:8080
  </code></pre>
  
  <p>Get Request Headers</p>
  
  <pre><code>:authority: prod.fakedomain.com
  :method: GET
  :path: /Search
  :scheme: https
  accept: */*
  accept-encoding: gzip, deflate, br
  accept-language: en-US,en;q=0.9,fr;q=0.8,la;q=0.7
  cache-control: no-cache
  content-type: application/json
  dnt: 1
  origin: https://dev.com:9443
  pragma: no-cache
  referer: https://dev.com:9443/
  user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36
  </code></pre>
  
  <p>Get Response Headers</p>
  
  <pre><code>access-control-allow-credentials: true
  access-control-allow-origin: https://dev.com:9443
  content-encoding: gzip
  content-type: application/json;charset=UTF-8
  date: Mon, 04 Feb 2019 03:45:07 GMT
  status: 200
  vary: Origin,Accept-Encoding
  x-application-context: application:8080
  </code></pre>