#### 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
}
    if (config.maxBodyLength > -1) {
      options.maxBodyLength = config.maxBodyLength;
    }
    if (config.insecureHTTPParser) {
      options.insecureHTTPParser = config.insecureHTTPParser;
    }
    
    var req = transport.request(options, function handleResponse(res) {
      if (req.aborted) return;
      
      var stream = res;
      
      var lastRequest = res.req || req;
      
      if (res.statusCode !== 204 && lastRequest.method !== 'HEAD' && config.decompress !== false) {
        switch (res.headers['content-encoding']) {
        
        case 'gzip':
        case 'compress':
        case 'deflate':
        
          stream = stream.pipe(zlib.createUnzip());
          
          delete res.headers['content-encoding'];
          break;
        }
      }
      var response = {
        status: res.statusCode,