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)

lib/adapters/xhr.js
}
    }
    
    if (typeof config.onDownloadProgress === 'function') {
      request.addEventListener('progress', config.onDownloadProgress);
    }
    
    if (typeof config.onUploadProgress === 'function' && request.upload) {
      request.upload.addEventListener('progress', config.onUploadProgress);
    }
    if (config.cancelToken) {
      
      config.cancelToken.promise.then(function onCanceled(cancel) {
        if (!request) {
          return;
        }
        request.abort();
        reject(cancel);
        
        request = null;
      });
    }
    if (requestData === undefined) {
      requestData = null;
    }
    
    request.send(requestData);
  });
};