title: Resource interpreted as Document but transferred with MIME type application/csv
body: <p>I have a button that downloads a CSV file. 
  The file seems to download fine but, I get the following warning. 
  This warning seems to only appear in chrome. </p>
  
  <blockquote>
    <p>Resource interpreted as Document but transferred with MIME type application/csv:</p>
  </blockquote>
  
  <p>This is where I set the CSV header.  </p>
  
  <pre><code>/**
  * Set the PHP mime header
  *
  * This will overwrite any previous headers
  *
  * @param string $header any custom headers that need to be set
  *
  * @return void
  * @access public
  */
  function setHeader($header='')
  {
      if ($header) {
          // set custom headers
          header($header);
      } else {
          header('Content-Type: application/csv');
          header('Content-Disposition: attachment; filename="'.$this-&gt;_filename.'";');
  
          //This is known that Internet Explorer has problems with SSL connection (https).
          //http://support.microsoft.com/default.aspx?scid=kb;en-us;812935
          //http://support.microsoft.com/default.aspx?scid=kb;en-us;316431
          // do not send no cache header in https for IE
  
          // get protocol information
          $url_info = parse_url(current_url());
          $protocol = (isset($url_info['scheme'])) ? $url_info['scheme'] : NULL;
          $using_ie6_8 = isset ($_SERVER['HTTP_USER_AGENT']) ? preg_match('/(MSIE\s[0-8]+\.)/', $_SERVER['HTTP_USER_AGENT']) : FALSE;
          if (!is_null($protocol) &amp;&amp; $protocol == 'https' &amp;&amp; $using_ie6_8) {
              header('Cache-Control: private, max-age=0, must-revalidate');
              header('Pragma: private');
              header('Expires: '.gmdate('D, d M Y H:i:s', time()-3600).' GMT');
  
          }
  
      }
  
  }//end setHeader()
  </code></pre>
  
  <p><strong>response header</strong>  </p>
  
  <pre><code>Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0
  Connection:keep-alive
  Content-Disposition:attachment; filename="submission_log.csv";
  Content-Type:application/csv
  Date:Thu, 22 Sep 2016 04:59:06 GMT
  Expires:Thu, 19 Nov 1981 08:52:00 GMT
  Pragma:no-cache
  Server:openresty
  Transfer-Encoding:chunked
  X-Content-Type-Options:nosniff
  X-Frame-Options:SAMEORIGIN
  </code></pre>
  
  <p><strong>request header</strong></p>
  
  <pre><code>Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
  Accept-Encoding:gzip, deflate
  Accept-Language:en-US,en;q=0.8
  Cache-Control:max-age=0
  Connection:keep-alive
  Content-Length:6252
  Content-Type:multipart/form-data; boundary=----WebKitFormBoundary4CxCF8KLzdtoGRO2
  Cookie:lastSelectedLinkId=2661; lastSelectedAssetId=2151; SQ_SYSTEM_SESSION=o44hori3h2fcu5ltm29u6rv2k44bq1tu6v3364pdi8jn273scebnjm3lsuik5teasneeh664j98o3ajbur6p39kque68qgjohkktsk3; _ga=GA1.2.545099348.1472451817
  Host:matrixdev.squiz.net
  Origin:http://matrixdev.squiz.net
  Referer:http://matrixdev.squiz.net/_admin/?SQ_BACKEND_PAGE=main&amp;backend_section=am&amp;am_section=edit_asset&amp;assetid=2151&amp;sq_asset_path=70%2C2151&amp;sq_link_path=71%2C2661&amp;asset_ei_screen=log
  Upgrade-Insecure-Requests:1
  User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36
  </code></pre>