Fix location data bug for string interpolations

Fix another case about #3514
In the case that heredoc starts with `\n`, location in tokens are broken.
```coffeescript
"""
#{b}
"""
```

Without this patch, `b`'s token is:
```
[ 'IDENTIFIER',
  'b',
  { first_line: 1, first_column: 1, last_line: 1, last_column: 1 } ]
```

With this patch:
```
[ 'IDENTIFIER',
  'b',
  { first_line: 1, first_column: 2, last_line: 1, last_column: 2 } ]
```