Cloning prototypes with getter

[oroce]

We are using clone in our logger: https://github.com/purposeindustries/node-logify-logstash-transport/blob/master/index.js#L20

If we are trying to clone a http.ServerResponse instance the module will throw an exception, because headersSent property has only getter: https://github.com/joyent/node/blob/7c0419730b237dbfa0ec4e6fb33a99ff01825a8f/lib/_http_outgoing.js#L398-L402

The added code does the follow:

1. Save prototype into proto variable if it has prototype or we can figure it out
2. If it has prototype it will try to find out the descriptors of the property
3. If the property has descriptors but it doesnt have setter we will move to next property (we can safely ignore setting the property on the child object because Object.create already created the getter on child.)

[pvorb]

Thanks a lot for this PR. I had a busy time the last few weeks, so I didn't find the time to merge it.

[oroce]

haha i totally forgot i did this pr. thanks for merging it!

[pvorb]

Me too. Just stumbled upon it a few days ago.