not include attributes which are not JSON types');

    test(function() {
        var map = interfaceFrom('interface A { [Default] object toJSON(); DOMString bar(); };').default_to_json_operation();
        assert_equals(map.size, 0);
    }, 'should not include operations');

    test(function() {
        var map = interfaceFrom('interface A { [Default] object toJSON(); attribute DOMString bar; };').default_to_json_operation();
        assert_equals(map.size, 1);
        assert_true(map.has("bar"));
       