declare urls property in wfs tile

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1148 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Tile/WFS.js

@@ -12,7 +12,9 @@ OpenLayers.Tile.WFS.prototype =
     /** @type Array(OpenLayers.Feature)*/ 
     features: null,
 
-
+    /** @type Array(String) */
+    urls: null,
+    
     /** 
     * @constructor
     *
@@ -40,6 +42,7 @@ OpenLayers.Tile.WFS.prototype =
         for(var i=0; i < this.features.length; i++) {
             this.features[i].destroy();
         }
+        this.urls = null;
         OpenLayers.Tile.prototype.destroy.apply(this, arguments);
     },