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
request: request
      };
      settle(resolve, reject, response);
      
      request = null;
    };
    
    request.onerror = function handleError() {
      
      
      reject(createError('Network Error', config, null, request));
      
      request = null;
    };
    
    request.ontimeout = function handleTimeout() {
      reject(createError('timeout of ' + config.timeout + 'ms exceeded', config, 'ECONNABORTED',
        request));
      
      request = null;
    };
    
    
    
    if (utils.isStandardBrowserEnv()) {
      var cookies = require('./../helpers/cookies');
      
      var xsrfValue = (config.withCredentials || isURLSameOrigin(config.url)) && config.xsrfCookieName ?
          cookies.read(config.xsrfCookieName) :
          undefined;