Data can be wrong in https://github.com/babel/babel-preset-env/blob/master/src/plugins.js.

We're using https://kangax.github.io/compat-table/es6/ now

There is also the issue of bugs in babel, bugs in the implementation, incomplete implementations (it supports the basic test of a feature but not everything), etc. This will require a lot of work to figure out but shouldn't be too bad with testing/attention to detail.

Can also use https://github.com/sdkennedy/babel-preset-target