Incorrect inspect() behavior for some nested lists

[front-endian]

When calling inspect() on a set of nested lists wrapped in square brackets you sometimes get unexpected results. The following is one of the simplest versions of this bug that I have found.

list_bug.scss

$example: [() (())];

@debug $example;
@debug inspect($example);

Actual results

libsass 3.5.4

/path/to/list_bug.scss:3 DEBUG: [() ()]
/path/to/list_bug.scss:4 DEBUG: [(() ())]

Expected result

Dart Sass 1.2.1
Ruby Sass 3.5.2

/path/to/list_bug.scss:3 DEBUG: [() ()]
/path/to/list_bug.scss:4 DEBUG: [() ()]

version info:

$ sassc -v
sassc: 3.4.8
libsass: 3.5.4
sass2scss: 1.1.1
sass: 3.5

http://libsass.ocbnet.ch/srcmap/#JGV4YW1wbGU6IFsoKSAoKCkpXTsKCkBkZWJ1ZyAkZXhhbXBsZTsKQGRlYnVnIGluc3BlY3QoJGV4YW1wbGUpOwo=