fix the bug: when cookie value can not been decodeURIComponent will throw error

when i use this plugin read a cookie whitch its value is "%u5317%u4eac", the plugin throw the "URIError: URI malformed". in chrome 25.0.1364.172 m, the others scripts was blocked.
I found out it happened at method decoded (line 24) through debug the code, and I fixed it. but i m not very sure this way is the best way, for reference only.

I m not good at English, holp you can understand what i m saying.