(x, y)(x, y)(x, y)

var polyCoordinates = [
    new google.maps.LatLng(x, y),
    new google.maps.LatLng(x, y),
    new google.maps.LatLng(x, y)
  ];

while ($row = mysql_fetch_array($query)) {
    echo "new google.maps.LatLng(" . $row['coordinate'] . "),";
}