Nested ES classes with constructors not supported

[itlgit]

Hi, the transformer fails when processing an AMD module which have nested ES classes defining constructors.

define(['exports', 'require'], function(exports, require) {
  class MyClass {
    constructor() {
      this.foo = 'bar';
      this._helper = new Helper();
    }
  }

  class Helper {
    constructor() {
      this.name = 'Helper';
    }
    init() {
      // THIS NESTED CLASS WILL FAIL
      this._private = class Helper {
        constructor() {
          this.value = 123;
        }
      }
      this._util = new Util();
    }
  }

  function Util() {
    this.name = 'Util';
    this._private = class Helper {
      constructor() {
        this.value = 123;
      }
    }
  }

  exports.MyClass = MyClass;
});

This results in the error

SyntaxError: Line 16, column 19: Duplicate constructor method in class
    at constructError (/home/user/node_modules/cherow/dist/umd/cherow.js:5625:21)
    at report (/home/user/node_modules/cherow/dist/umd/cherow.js:5664:7)
    at parseClassElement (/home/user/node_modules/cherow/dist/umd/cherow.js:4398:19)

This works fine if the "constructor" method isn't defined.