Incorrect logging message after decorator the $log

Incorrect logging message after decorator the $log

I'm trying to decorate the angular's $log factory to put the timestamp of
the message in the log.
It works pretty well until now, except for this behavior:
When I log with default configuration of angular, I receive:
message for Object {name: "bryan", message: "was here"} thrid argument
Plunker
After creating the decorator, the logs became this:
["message for", Object, "thrid argument"]
Plunker - The code is here
So, the Object was not expanded to the console, and I need to click at the
message to see the full object.
Does anyone know what I'm missing? Or know a better way to do this?