title: Adding Google Maps InfoWindow from data features generates error: "b.get is not a function"
body: <p>I'm trying to add a info window to each of my features in a Google Map. In the example from Google (<a href="https://developers.google.com/maps/documentation/javascript/infowindows" rel="nofollow noreferrer">https://developers.google.com/maps/documentation/javascript/infowindows</a>) They add an info window directly to a marker. I don't have a explicit market to add my info window, instead I have a collection of data that I imported from a GeoJson file. </p>
  
  <p>I can add a click listener to each feature, and create a new InfoWindow with the correct description. However, I get an error (<code>b.get is not a function</code>) when opening the InfoWindow.</p>
  
  <pre><code>function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
      zoom: 2,
      center: new google.maps.LatLng(28.7, -15.0),
      mapTypeId: 'terrain'
  });
  
  map.data.loadGeoJson('http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/4.5_week.geojson');
  
  map.data.setStyle(function (feature) {
      var magnitude = feature.getProperty('mag');
      return {
          icon: getCircle(magnitude)
      };
  });
  
  map.data.addListener('click', function (event) {
      var infowindow = new google.maps.InfoWindow({
          content: event.feature.getProperty('place')
      });
      infowindow.open(map, event.feature);
  });
  </code></pre>