Code: Fixed another segmentation fault

With this, the travis-ci build doesn't throw seg-fault. :relaxed: 

There are still two test cases failing on Ubuntu and one on Windows.

@mgreter, can you reproduce these? In Windows [this test](https://github.com/sass/node-sass/blob/26c1bf31be8e412f463b15b2282b5aa1ae08cd28/test/test.js#L263-L283) fails as upstream returns:

```json
  sources:
   [ '..\\included_files.scss',
     '..\\sample.scss',
     '..\\image_path.scss' ],
```

instead of : 

```json
  sources:
   [ '../included_files.scss',
     '../sample.scss',
     '../image_path.scss' ],
```

In Ubuntu, these [two tests fail](https://github.com/sass/node-sass/blob/26c1bf31be8e412f463b15b2282b5aa1ae08cd28/test/test.js#L223-L261) owing to the fact that upstream puts this comment `/*# sourceMappingURL=../out.css.map */` in CSS instead of `/*# sourceMappingURL=out.css.map */`.