Filter strategy constructor should not need filter, r=tschaub,fredj (closes #2841)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10879 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Strategy/Filter.js

@@ -45,14 +45,10 @@ OpenLayers.Strategy.Filter = OpenLayers.Class(OpenLayers.Strategy, {
      *
      * Parameters:
      * options - {Object} Optional object whose properties will be set on the
-     *     instance.  Strategy must be constructed with at least a <filter> 
-     *     property.
+     *     instance.
      */
     initialize: function(options) {
         OpenLayers.Strategy.prototype.initialize.apply(this, [options]);
-        if (!this.filter || !(this.filter instanceof OpenLayers.Filter)) {
-            throw new Error("Filter strategy must be constructed with a filter");
-        }
     },
 
     /**
@@ -102,7 +98,7 @@ OpenLayers.Strategy.Filter = OpenLayers.Class(OpenLayers.Strategy, {
      * Method: handleAdd
      */
     handleAdd: function(event) {
-        if (!this.caching) {
+        if (!this.caching && this.filter) {
             var features = event.features;
             event.features = [];
             var feature;