Merge branch 't/10666'

Author: Reinmar

CHANGES.md

@@ -5,6 +5,7 @@ CKEditor 4 Changelog
 
 Fixed Issues:
 
+* [#10666](http://dev.ckeditor.com/ticket/10666): Fixed tools.isArray not working cross frame.
 * [#10910](http://dev.ckeditor.com/ticket/10910): Fixed error thrown on Internet Explorer 9 in Compatibility Mode.
 * [#10868](http://dev.ckeditor.com/ticket/10868): Prevent from Internet Explorer 8 crashing when applying a cite style.
 * [#10915](http://dev.ckeditor.com/ticket/10915): CSS filter in Kama skin pull request.

core/tools.js

@@ -223,7 +223,7 @@
 		 * @returns {Boolean} `true` if the object is an Array, otherwise `false`.
 		 */
 		isArray: function( object ) {
-			return ( !!object && object instanceof Array );
+			return Object.prototype.toString.call( object ) == '[object Array]';
 		},
 
 		/**