#### 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
var proxy = config.proxy;
    if (!proxy && proxy !== false) {
      var proxyEnv = protocol.slice(0, -1) + '_proxy';
      var proxyUrl = process.env[proxyEnv] || process.env[proxyEnv.toUpperCase()];
      if (proxyUrl) {
        var parsedProxyUrl = url.parse(proxyUrl);
        var noProxyEnv = process.env.no_proxy || process.env.NO_PROXY;
        var shouldProxy = true;
        if (noProxyEnv) {
          var noProxy = noProxyEnv.split(',').map(function trim(s) {
            return s.trim();
          });
          shouldProxy = !noProxy.some(function proxyMatch(proxyElement) {
            if (!proxyElement) {
              return false;
            }
            if (proxyElement === '*') {
              return true;
            }
            if (proxyElement[0] === '.' &&
                parsed.hostname.substr(parsed.hostname.length - proxyElement.length) === proxyElement) {
              return true;
            }
            return parsed.hostname === proxyElement;
          });
        }
        if (shouldProxy) {
          proxy = {
            host: parsedProxyUrl.hostname,
            port: parsedProxyUrl.port,