More robust array type check. p=mwootendev, r=me (closes #2959)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12095 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/ModifyFeature.js

@@ -215,7 +215,7 @@ OpenLayers.Control.ModifyFeature = OpenLayers.Class(OpenLayers.Control, {
         this.deleteCodes = [46, 68];
         this.mode = OpenLayers.Control.ModifyFeature.RESHAPE;
         OpenLayers.Control.prototype.initialize.apply(this, [options]);
-        if(!(this.deleteCodes instanceof Array)) {
+        if(!(OpenLayers.Util.isArray(this.deleteCodes))) {
             this.deleteCodes = [this.deleteCodes];
         }
         var control = this;