Drop transpilation

[nikku]

What should we do?

Given that we lifted our language level to ES2018 we can now drop our transpilation of classes.

Why should we do it?

Ensure that our bundles are as small as possible.

[barmac]

We could probably drop transpilation for dmn-js-drd, but for Inferno-based libraries we still need to somehow handle JSX.

AFAIK we don't transpile classes since the migration, e.g. https://unpkg.com/browse/dmn-js-decision-table@15.0.0/lib/Editor.js

[nikku]

I'd love us to transpile only what is absolutely necessary. Right now we transpile many things, and we cannot use @babel/preset-env to define a clear target (ES2018).

[barmac]

Ideally, I'd use babel only to support the latest browsers. This is what we declared anyway. ES2018 was set as a target to prevent transpilation, but in dmn-js we can't work without it at the moment due to Inferno.