Workaround for Webpack issue

[guybedford]

This implements a workaround for webpack/webpack#11613 that is compatible both with Node.js and Webpack.

[weswigham]

I'm more comfortable with #129, since this would pollute our wrapper code in a strange, unexplainable way, while that PR gets us closer to just having webpack respect the module entrypoint, as it used to.

[weswigham]

Like, I just don't wanna handle two runtimes which do different things with the import using the same code. Moreover, the only reason there's a wrapper is so that in node we only load one copy of the library - in webpack, the module field made sure that one copy was the esm copy. We really just wanna continue that behavior.

[orta]

Thanks guy! #129 is now merged and deployed