Is the fall through essential here?

The following switch case has no `break` statement at the end.

https://github.com/domchristie/needles/blob/master/dist/needles-worker.js#L285-L286

```js
    case 'set':
      this[event.data.key] = event.data.value; // <-- after this statement
    case 'record':
```

Is it intentional?