title: jquery jqXHR.getResponseHeader('Location'), is null
body: <p>in my ajax call the <code>responseHeader('Location')</code> is FF always empty. Can anybody help me? By the way it is a CORS.</p>
  
  <pre><code>$.ajax({
                  url: VIDEOS_UPLOAD_SERVICE_URL,
                  method: 'POST',
                  contentType: 'application/json',
                  headers: {
                      Authorization: 'Bearer ' + accessToken,
                      'x-upload-content-length': file.size,
                      'x-upload-content-type': file.type
                  },
                  data: JSON.stringify(metadata)
              }).done(function(data, textStatus, jqXHR) {
                  resumableUpload({
                      url: jqXHR.getResponseHeader('Location'),
                      file: file,
                      start: 0
                  });
              });
  </code></pre>