nl_tokens: Gets defined after initialization by _applyAttributeBindings
pl_tokens: function ( key , value ) { var attributeName = this . _unspecifiedAttributeBindings && this . _unspecifiedAttributeBindings [ key ] ; if ( attributeName ) { this . _setupAttributeBindingObservation ( key , attributeName ) ; } defineProperty ( this , <mask> ) ; return set ( this , key , value ) ; }