prototype: Make sure $w always returns an array.

CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Make sure $w always returns an array. [Andrew Dupont, Tobie Langel]
+
 * Add more tests to Hash. [Mislav Marohnić]
 
 * Performance enhancements to $A. Closes #9464. [Samuel Lebeau]

src/array.js

@@ -128,6 +128,7 @@ if (!Array.prototype.lastIndexOf) Array.prototype.lastIndexOf = function(item, i
 Array.prototype.toArray = Array.prototype.clone;
 
 function $w(string) {
+  if (!Object.isString(string)) return [];
   string = string.strip();
   return string ? string.split(/\s+/) : [];
 }

test/unit/array.html

@@ -204,6 +204,11 @@
     test$w: function(){ with(this) {
       assertEnumEqual(['a', 'b', 'c', 'd'], $w('a b c d'));
       assertEnumEqual([], $w(' '));
+      assertEnumEqual([], $w(''));
+      assertEnumEqual([], $w(null));
+      assertEnumEqual([], $w(undefined));
+      assertEnumEqual([], $w());
+      assertEnumEqual([], $w(10));
       assertEnumEqual(['a'], $w('a'));
       assertEnumEqual(['a'], $w('a '));
       assertEnumEqual(['a'], $w(' a'));