Create fields of members without dependencies

[github-nilsson]

It would be great if lebab could identify and move class member properties with constant initializations to fields automatically. I.e.

function A(b) {
  this.a = [];
  this.b = b;
}

would become

class A {
  a = [];
  constructor(b) {
    this.b = b;
  }
}

[nene]

Yeah, that would be nice. But it would have to be a separate transform as it's both a stylistic preference and IIRC member fields aren't part of the older ECMAScript classes spec.

Probably best to first perform the class transform and then apply this one already on top of a class.

But I'm not really doing any new developments on this library... so unless somebody does a pull request, this likely won't get implemented.