#### 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
requestHeaders[config.xsrfHeaderName] = xsrfValue;
      }
    }
    
    if ('setRequestHeader' in request) {
      utils.forEach(requestHeaders, function setRequestHeader(val, key) {
        if (typeof requestData === 'undefined' && key.toLowerCase() === 'content-type') {
          
          delete requestHeaders[key];
        } else {
          
          request.setRequestHeader(key, val);
        }
      });
    }
    
    if (!utils.isUndefined(config.withCredentials)) {
      request.withCredentials = !!config.withCredentials;
    }
    
    if (responseType && responseType !== 'json') {
      request.responseType = config.responseType;
    }
    
    if (typeof config.onDownloadProgress === 'function') {
      request.addEventListener('progress', config.onDownloadProgress);
    }
    
    if (typeof config.onUploadProgress === 'function' && request.upload) {
      request.upload.addEventListener('progress', config.onUploadProgress);