Arrow functions breaks require-optimization

[sarjanen]

Like title says, it seems like arrow functions breaks require-optimization. I'm getting error on this:

import React from 'react';

export default class Foo extends React.Component {
  bar() { }
  render() { return null; }
}

But not on:

import React from 'react';

export default class Foo extends React.Component {
  bar = () =>  { }
  render() { return null; }
}

[ljharb]

Class fields should never have functions in them; but it seems reasonable for the rule to handle this case.