Nan::ObjectWrap Docs: https://github.com/nodejs/nan/blob/master/doc/object_wrappers.md#api_nan_object_wrap

Prior to this, all wrapper Objects would never be deleted, allowing memory to grow unbounded.

Example:
The following, would leak WrapperObjects, and never

```
while (true) {
  new sass.types.String(‘I LEAK’);
}
```