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/Util.js

@@ -58,6 +58,22 @@ OpenLayers.Util.isElement = function(o) {
     return !!(o && o.nodeType === 1);
 };
 
+/**
+ * Function: isArray
+ * Tests that the provided object is an array.
+ * This test handles the cross-IFRAME case not caught
+ * by "a instanceof Array" and should be used instead.
+ * 
+ * Parameters:
+ * a - {Object} the object test.
+ * 
+ * Returns
+ * {Boolean} true if the object is an array.
+ */
+OpenLayers.Util.isArray = function(a) {
+	return (Object.prototype.toString.call(a) === '[object Array]');
+};
+
 /** 
  * Maintain existing definition of $.
  */
@@ -346,7 +362,7 @@ OpenLayers.Util.onImageLoadError = function() {
     this._attempts = (this._attempts) ? (this._attempts + 1) : 1;
     if (this._attempts <= OpenLayers.IMAGE_RELOAD_ATTEMPTS) {
         var urls = this.urls;
-        if (urls && urls instanceof Array && urls.length > 1){
+        if (urls && OpenLayers.Util.isArray(urls) && urls.length > 1){
             var src = this.src.toString();
             var current_url, k;
             for (k = 0; current_url = urls[k]; k++){