title: containsLocation not working
body: <p>I'm trying to retrieve a boolean result using 'google.maps.geometry.poly.containsLocation', the problem is than isnt returning nothing, I don't know if I need to called it inside of a eventListener, but when I try to called it starts saying that 'pos' is undefined, then when I intialize pos, it says that "lng" is not defined, something is wrong with my code or I'm not doing it the right way.</p>
  
  <p>JS:</p>
  
  <pre><code>var map;
  
  function initMap() {
      map = new google.maps.Map(document.getElementById('map'), {
      center: {lat: 41.185083, lng: -8.698814},
      zoom: 12,
      mapTypeId: google.maps.MapTypeId.TERRAIN
    });
  
  
    var infoWindow = new google.maps.InfoWindow({map: map});
    // Try HTML5 geolocation.
    if (navigator.geolocation) {
      navigator.geolocation.getCurrentPosition(function(position) {
        var pos = {
          lat: position.coords.latitude,
          lng: position.coords.longitude
        };
  
  
        infoWindow.setPosition(pos);
        infoWindow.setContent('You are Here.');
        map.setCenter(pos);
      }, function() {
        handleLocationError(true, infoWindow, map.getCenter());
      });
    } else {
      // Browser doesn't support Geolocation
      handleLocationError(false, infoWindow, map.getCenter());
    }
  
  
  
     // Define the LatLng coordinates for Zone.
    var zone_Coords = [
      {lat: 41.194975, lng: -8.683102},
      {lat: 41.183693, lng: -8.703740},
      {lat: 41.205572, lng: -8.717563},
      {lat: 41.203185, lng: -8.690135},
      {lat: 41.194975, lng: -8.683102}
    ];
  
     // Construct the Zone.
    var zone = new google.maps.Polygon({
      paths: zone_Coords,
      strokeColor: '#023bca',
      strokeOpacity: 0.8,
      strokeWeight: 2,
      fillColor: '#0748eb',
      fillOpacity: 0.35
    });
  
    zone3.setMap(map);
  
  var isWithinPolygon = google.maps.geometry.poly.containsLocation(pos, zone);
      console.log(isWithinPolygon);
  
  }
  
  function handleLocationError(browserHasGeolocation, infoWindow, pos) {
    infoWindow.setPosition(pos);
    infoWindow.setContent(browserHasGeolocation ?
                          'Error: The Geolocation service failed.' :
                          'Error: Your browser doesn\'t support geolocation.');
  }
  </code></pre>