Fix loading lineNumber from coffeescript token

- Using the latest version of the `coffeescript` code (From the website)
- `CoffeeScript.tokens(text)` returns tokens like:

```json
[
  "IDENTIFIER",
  "variable",
  {
    "first_line":0,
    "first_column":0,
    "last_line":0,
    "last_column":1
  }
]
```
This patch checks to see if the lineNumber variable has the key `first_line`, in which case it uses `lineNumber["first_line"]` instead.