Fix issue with markers virtual DOM (see GoogleWebComponents#397)

Author: bertie-wheen

google-map-marker.html

@@ -315,7 +315,7 @@
         },
 
         _clickEventsChanged: function() {
-          if (this.map) {
+          if (this.marker) {
             if (this.clickEvents) {
               this._forwardEvent('click');
               this._forwardEvent('dblclick');
@@ -329,7 +329,7 @@
         },
 
         _dragEventsChanged: function() {
-          if (this.map) {
+          if (this.marker) {
             if (this.dragEvents) {
               this._forwardEvent('drag');
               this._forwardEvent('dragend');
@@ -343,7 +343,7 @@
         },
 
         _mouseEventsChanged: function() {
-          if (this.map) {
+          if (this.marker) {
             if (this.mouseEvents) {
               this._forwardEvent('mousedown');
               this._forwardEvent('mousemove');