bugfix - array.length equals to NaN

I don't know how to solve this in a different approach.

```javascript
Array.call(this, ports.length);
```

does not add the `.length` property to `this` resulting in `this.length == NaN` after the first `this.length++`

We can't do `this.__proto__ = Array.prototype` because that would destroy the `EventEmiter` prototype.

So the only solution I see is to initialize `this.length = 0`.

Cheers.