when we remove popups or layers from the map, we have to set their 'map' properties back to null

git-svn-id: http://svn.openlayers.org/trunk/openlayers@545 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -150,6 +150,7 @@ OpenLayers.Map.prototype = {
     removeLayer: function(layer) {
         this.layerContainerDiv.removeChild(layer.div);
         this.layers.remove(layer);
+        layer.map = null;
         this.events.triggerEvent("removelayer");
     },
 
@@ -199,6 +200,7 @@ OpenLayers.Map.prototype = {
         if (popup.div) {
             this.layerContainerDiv.removeChild(popup.div);
         }
+        popup.map = null;
     },
         
     /**