#### 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/http.js
statusText: res.statusMessage,
        headers: res.headers,
        config: config,
        request: lastRequest
      };
      if (config.responseType === 'stream') {
        response.data = stream;
        settle(resolve, reject, response);
      } else {
        var responseBuffer = [];
        var totalResponseBytes = 0;
        stream.on('data', function handleStreamData(chunk) {
          responseBuffer.push(chunk);
          totalResponseBytes += chunk.length;
          
          if (config.maxContentLength > -1 && totalResponseBytes > config.maxContentLength) {
            
            rejected = true;
            stream.destroy();
            reject(new AxiosError('maxContentLength size of ' + config.maxContentLength + ' exceeded',
              AxiosError.ERR_BAD_RESPONSE, config, lastRequest));
          }
        });
        stream.on('aborted', function handlerStreamAborted() {
          if (rejected) {
            return;
          }
          stream.destroy();
          reject(new AxiosError(
            'maxContentLength size of ' + config.maxContentLength + ' exceeded',