Fixed mixin with Underscore.

diff --git a/underscore.date.js b/underscore.date.js
old mode 100755 (executable)
new mode 100644 (file)
index 076a5c6..7118e4b
--- a/underscore.date.js
+++ b/underscore.date.js
@@ -387,7 +387,7 @@
     // Integrate with Underscore.js
     } else {
         if (this._ !== undefined) {
-            this._.mixin(_date);
+            this._.mixin({date: _date});
         }
         this._date = _date;
     }