UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36

Steps to reproduce the problem:
1. Check the CommandLine API s Command Name
2. The Same KeyName of Define property at Object.prototype
3. Developer Tool's Console become unresponsive

What is the expected behavior?
Developer Tool's Console become unresponsive

What went wrong?
Developer Tool's Console become unresponsive

Did this work before? N/A 

Chrome version: 51.0.2704.103  Channel: n/a
OS Version: OS X 10.11.5
Flash Version: Shockwave Flash 22.0 r0

I check at this.

Object.defineProperty(Object.prototype, 'copy', {
    value : function () {
        return Object.assign({},this)
    }
});