Javascript: Adjusting global names of LinkedList solutions so that all the tests can pass

Maybe I misunderstood, the intent, but in order to get 

```
$ mocha --recursive
```

To pass, I needed to change the names of the globals used


```
  $ mocha --recursive

  ․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․․

  55 passing (13ms)

```


Adjusting global names of LinkedList solutions so that all the tests can be run and passed otherwise 2_2 clobbers 2_1 and 2_3 clobbers 2_2