I have axios@0.15.2

If this HTML is run, some requests will be cancelled by Chrome:

    <html>
    <head>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.15.2/axios.js"></script>
    </head>
        <script>
        var promises = [];
        window.onload = function() {
            for (var i = 0; i < 4; i++) {
                var promise = axios.get('some url which causes ERR_CONNECTION_CLOSED');
                promises.push(promise);
            }
        }
       </script>
    </html>

![Cancelled](https://cloud.githubusercontent.com/assets/4506837/20349972/9123cef0-ac2e-11e6-93db-0ec66f205382.png)

But promises which turned into cancelled request won't be fulfilled:

![notfulfilled](https://cloud.githubusercontent.com/assets/4506837/20350023/d2146c4e-ac2e-11e6-89bc-983233628d09.png)

test/specs/requests.spec.js
}
    axios('/foo', {
      responseType: 'arraybuffer'
    }).then(function (data) {
      response = data;
    });
    getAjaxRequest().then(function (request) {
      request.respondWith({
        status: 200,
        response: str2ab('Hello world')
      });
      setTimeout(function () {
        expect(response.data.byteLength).toBe(22);
        done();
      }, 100);
    });
  });
  it('should support URLSearchParams', function (done) {
    var params = new URLSearchParams();
    params.append('param1', 'value1');
    params.append('param2', 'value2');
    axios.post('/foo', params);
    getAjaxRequest().then(function (request) {
      expect(request.requestHeaders['Content-Type']).toBe('application/x-www-form-urlencoded;charset=utf-8');
      expect(request.params).toBe('param1=value1&param2=value2');
      done();
    });
  });
});