Allowing parameter-less mixins to be called without parentheses.

document_parser.cpp

@@ -118,7 +118,7 @@ namespace Sass {
   Node Document::parse_mixin_arguments()
   {
     Node args(line_number, Node::arguments);
-    lex< exactly<'('> >();
+    if (lex< exactly<'('> >()) {
       if (!peek< exactly<')'> >(position)) {
         args << parse_argument();
         while (lex< exactly<','> >()) {
@@ -126,6 +126,7 @@ namespace Sass {
         }
       }
       lex< exactly<')'> >();
+    }
     return args;
   }