attach to this rather than window to support web workers (closes #8)

Author: davidchambers

base64.js

@@ -1,7 +1,7 @@
 ;(function () {
 
   var
-    object = typeof exports != 'undefined' ? exports : window,
+    object = typeof exports != 'undefined' ? exports : this, // #8: web workers
     chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=',
     INVALID_CHARACTER_ERR = (function () {
       // fabricate a suitable error object