Unquoted domains produce invalid CSS

[Aran-Fey]

Omitting the quotes inside the domain() selector successfully compiles to invalid CSS instead of showing an error message:

Input:

@-moz-document domain(example.com){}

Compilation:

aran-fey@Starlight ~/D/temp {e}> stylus test.styl -o test.css
  compiled test.css

Output:

@-moz-document domain((example.com)) {}