…able-js into alexvictoor-no-constructor-returns

…2072)

* Call super()" before this in constructors

* Fix issue with MapIterator re-setting the next method

…wsers might re-compile immutable

Replace buble by babel

Define "exports" in package.json

…lyfill

```
Type '(Iterable<T> | ArrayLike<T>) & IndexedCollectionImpl<unknown>' is not assignable to type 'IndexedCollectionImpl<T>'.
  Type 'Iterable<T> & IndexedCollectionImpl<unknown>' is not assignable to type 'IndexedCollectionImpl<T>'.
    The types returned by 'toArray()' are incompatible between these types.
      Type 'unknown[]' is not assignable to type 'T[]'.
        Type 'unknown' is not assignable to type 'T'.
          'T' could be instantiated with an arbitrary type which could be unrelated to 'unknown'.

113   return isIndexed(value) ? value : IndexedSeq(value);
```