opened
jbpros
username_0
This is how the World constructor is now expected to call back:

``` javascript
this.World = function World(callback) {
  callback(this);
}
```

Calling back without a parameter is currently forbidden, leading to an exception:

``` javascript
this.World = function World(callback) {
  callback(); // error!
}
```

Cucumber is using the `new` keyword when calling the `World()` function. It means it could (and should) use the fresh World instance when no explicit one is passed to the callback.

``` javascript
this.World = function World(callback) {
  callback(); // would be the same as: callback(this)
}
```
Allow World constructor to callback without explicit world instance
issue