#### Is your feature request related to a problem? Please describe.
This is an optimazition of code.

#### Describe the solution you'd like
The following line of code comes from https://github.com/axios/axios/blob/master/lib/adapters/http.js#L403:
```js
reject(!cancel || (cancel && cancel.type) ? new CanceledError() : cancel);
```
It can be optimized as follows:
```js
reject(!cancel || cancel.type ? new CanceledError() : cancel);
```

#### Describe alternatives you've considered
When the code is executed to `(cancel && cancel.type)`, it means `!cancel` is false, so `cancel` is true, we can get `cancel.type` directly.

#### Additional context
no more

lib/adapters/xhr.js
}
    if (config.cancelToken || config.signal) {
      
      
      onCanceled = function(cancel) {
        if (!request) {
          return;
        }
        reject(!cancel || (cancel && cancel.type) ? new CanceledError() : cancel);
        request.abort();
        request = null;
      };
      config.cancelToken && config.cancelToken.subscribe(onCanceled);
      if (config.signal) {
        config.signal.aborted ? onCanceled() : config.signal.addEventListener('abort', onCanceled);
      }
    }
    if (!requestData) {
      requestData = null;
    }
    var protocol = parseProtocol(fullPath);
    if (protocol && [ 'http', 'https', 'file' ].indexOf(protocol) === -1) {
      reject(new AxiosError('Unsupported protocol ' + protocol + ':', AxiosError.ERR_BAD_REQUEST, config));
      return;
    }
    
    request.send(requestData);
  });
};