nl_tokens: imperfect ownKeys implemenation : in ES6 should also include symbol - keyed properties .
pl_tokens: function ( target ) { var handler = directProxies . get ( target ) ; if ( handler !== undefined ) { return handler . ownKeys ( handler . target ) ; } var <mask> = Reflect . getOwnPropertyNames ( target ) ; var l = + result . length ; var idx = 0 ; return { next : function ( ) { if ( idx === l ) throw StopIteration ; return result [ idx ++ ] ; } } ; }