Minify doesn't work in the REPL anymore

[xtuc]

See REPL

The error is the following: repl: traverse.clearCache is not a function.

/cc @boopathi

[existentialism]

Probably because current minify isn't compatible with babel 7? Seems to work fine with 6.x

On another note, we likely need to tie versions of preset-env and minify to the version flag passed in.

[xtuc]

Yes right @existentialism, there's the PR in WIP babel/minify#487.

Could we maybe add an error when calling preset-env/minify with an unsupported Babel version? babel-core exports its version IRC.

[hzoo]

Fixed at some point