Fix docstring

Author: ebidel

google-map.html

@@ -42,7 +42,7 @@
     Polymer('google-map-marker', {
 
       /**
-       * A latitude to center the map on.
+       * A Google Maps marker object.
        *
        * @property marker
        * @type google.maps.Marker
@@ -51,7 +51,7 @@
       marker: null,
 
       /**
-       * The underlying map object.
+       * The Google map object.
        *
        * @property map
        * @type google.maps.Map