return correct map overlay elem

src/ol/Map.js

@@ -379,6 +379,25 @@ ol.Map.prototype.moveByPx = function(dx, dy) {
     // call moveByPx on renderers
 };
 
+/**
+ * @param {ol.Loc} loc the location being requested 
+ * @returns {Object} the 
+ */
+ol.Map.prototype.getViewportPosition = function(loc) {
+    //TODO: delegate this to the renderers
+    //stub for now to get popups working
+    return {x: 200, y: 300};
+};
+
+/**
+ * @returns {Element} the map overlay element
+ */
+ol.Map.prototype.getMapOverlay = function() {
+    //TODO: delegate this to the renderers
+    //stub for now to get popups working
+    return this.mapOverlay_
+};
+
 /**
  * @export
  */