Pretty-printer prints comments above a case too late

[marijnh]

In parser.rs, we now have...

            case (
                 //the lexer can't tell the different kinds of stars apart ) :
                 token::BINOP(token::STAR)) {
                glob = true;
                p.bump();
            }

The comment used to be above the case, but ends up being printed after the "case (" part has already been output.

[brson]

I can no longer reproduce this issue. Instead of printing the comments too late, it now adds extra whitespace (#850).