Refactoring checkHost

[orenfromberg]

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

Motivation / Use-Case

I found the second condition in this line confusing:
https://github.com/webpack/webpack-dev-server/blob/master/lib/Server.js#L751

      if (!this.checkHost(connection.headers) || !this.checkHost(connection.headers, 'origin')) {

Specifically checkHost(connection.headers, 'origin'). The function is ostensibly going to check the Host header but in fact it is really checking the host described by the Origin header.

In order to make code easier to reason about, I refactored this to:

      if (!this.checkHost(connection.headers) || !this.checkOrigin(connection.headers)) {

Breaking Changes

Additional Info

[jsf-clabot]

All committers have signed the CLA.

[alexander-akait]

Thanks!