Adding babel env preset breaks example

I've been diving into webpack a little deeper than usual lately trying to get a nicer dev setup for a project of mine. It's a bit of a bigger project and in trying to get HMR working on the server and client, I was trying to figure out why the server portion wasn't working like this example. I figured out adding `babel-preset-env` breaks the example entirely. I'm not quite sure why since there are a lot of moving parts but I thought I'd at least start the conversation here.

I also made a diff of the changes the preset makes in the built server file [here](https://gist.github.com/okcoker/3fe0cf0f94e8000fc7ec11eb5f468c0e).

The fix for me in the meantime was to just move this preset to the production section of my `.babelrc` file. Maybe there is no way around this?