There is now way how to find out, which properties were defined for an parameter of an method. The current implementation is able to work only in the context method, where the parameter is defined. So for example 

function addProperty(where) {
   where.print = function () {}
}

the model know, that the where parameter has defined method print. But then when is code

var where = {}
addProperty(where);

the where variable doesn't have property print, because we don't "export" the property to the where variable.