Method add

src/main/java/org/dynjs/runtime/DynObject.java:633–640

(String e)

        }

        @Override
        public boolean add(String e) {
            if (! hasProperty(null, e)) {
                put(e, Types.UNDEFINED);
                return true;
            }
            return false;
        }

        @Override
        public boolean remove(Object o) {