Insert data dynamically with xml the coordinates in the heat map

I'm trying to use this code to read data from the xml parts coordinates instead of the data statically inserted into the code but does not work when done this way. Code:

function getPoints() {
  return [
                //new google.maps.LatLng(-26.20478566666, -51.0518355),                 
                //new google.maps.LatLng(-26.265426, -51.10279483333),
                //  new google.maps.LatLng(-26.265426, -51.10279483333),                    
                //  new google.maps.LatLng(-26.22920166666, -51.08537583333),
                //  new google.maps.LatLng(-26.21230783333, -51.0784765),
                //  new google.maps.LatLng(-26.21460016666,-51.07964916666),
                //  new google.maps.LatLng(-26.21396566666, -51.076862),
                //  new google.maps.LatLng(-26.23305616666, -51.05080116666),
                //  new google.maps.LatLng(-26.2335205, -51.05153366666),
                //  new google.maps.LatLng(-26.22982933333, -51.08531783333),
                //  new google.maps.LatLng(-26.20052716666, -51.09534966666),
                //  new google.maps.LatLng(-26.22196833333, -51.05161116666),
                //  new google.maps.LatLng(-26.20052716666, -51.09534966666),
                //  new google.maps.LatLng(-26.22196833333, -51.05161116666),
                //  new google.maps.LatLng(-26.22650916666, -51.08625616666),
                //  new google.maps.LatLng(-26.22650916666, -51.08625616666),
                //  new google.maps.LatLng(-26.22196833333, -51.05161116666),                   
                //  new google.maps.LatLng(-26.22650916666, -51.08625616666)

                    downloadUrl("dados.xml", function(data) 
                    {
                        var xml = data.responseXML;
                        var markers = xml.documentElement.getElementsByTagName("marker");
                        for (var i = 0; i < markers.length; i++) 
                        {                     
                             var point = new google.maps.LatLng
                             (
                              parseFloat(markers[i].getAttribute("lat")),
                              parseFloat(markers[i].getAttribute("lng"))
                              );                    
                        };              
                    }
                    );
  ];
}
function downloadUrl(url, callback) {
              var request = window.ActiveXObject ?
                  new ActiveXObject('Microsoft.XMLHTTP') :
                  new XMLHttpRequest;

              request.onreadystatechange = function() {
                if (request.readyState == 4) {
                  request.onreadystatechange = doNothing;
                  callback(request, request.status);
                }
              };

              request.open('GET', url, true);
              request.send(null);

The implementation I'm using is based on this example link