#### 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
reject(AxiosError.from(err, null, config, req));
    });
    
    req.on('socket', function handleRequestSocket(socket) {
      
      socket.setKeepAlive(true, 1000 * 60);
    });
    
    if (config.timeout) {
      
      var timeout = parseInt(config.timeout, 10);
      if (isNaN(timeout)) {
        reject(new AxiosError(
          'error trying to parse `config.timeout` to int',
          AxiosError.ERR_BAD_OPTION_VALUE,
          config,
          req
        ));
        return;
      }
      
      
      
      
      
      req.setTimeout(timeout, function handleRequestTimeout() {
        req.abort();
        var transitional = config.transitional || transitionalDefaults;
        reject(new AxiosError(
          'timeout of ' + timeout + 'ms exceeded',