Merge pull request #5 from omphalos/defineProperty

Use Object.defineProperty not __defineGetter__

lib/index.js

@@ -88,8 +88,10 @@
     return Object.keys(this)[i];
   };
 
-  Storage.prototype.__defineGetter__('length', function () {
+  Object.defineProperty(Storage.prototype, 'length', {
+    get: function() {
       return Object.keys(this).length;
+    }
   });
 
   Storage.prototype.___save___ = function () {