fix trailing comma

Author: James Halliday

lib/test.js

@@ -164,7 +164,7 @@ Test.prototype._assert = function assert (ok, opts) {
         ok : Boolean(ok),
         skip : defined(extra.skip, opts.skip),
         name : defined(extra.message, opts.message, '(unnamed assert)'),
-        operator : defined(extra.operator, opts.operator),
+        operator : defined(extra.operator, opts.operator)
     };
     if (has(opts, 'actual') || has(extra, 'actual')) {
         res.actual = defined(extra.actual, opts.actual);