nl_tokens: On success check whether the target object is indeed frozen .
pl_tokens: function ( ) { var trap = this . getTrap ( "freeze" ) ; if ( trap === undefined ) { // default forwarding behavior return Reflect . freeze ( this . target ) ; } var <mask> = trap . call ( this . handler , this . target ) ; success = ! ! success ; // coerce to Boolean if ( success ) { if ( ! Object_isFrozen ( this . target ) ) { throw new TypeError ( "can't report non-frozen object as frozen: " + this . target ) ; } } return success ; }