Now, when creating a remote object in renderer, the browser will
reference the corresponding object by storing it in a strong map. And
when the remote object in renderer is GCed, the corresponding object
will be dereferenced in browser.
Basic usage is:
remote = require 'remote'
Window = remote.require 'window'
w = new Window { width: 800, height: 600 }
Still need to do:
* Beter support for Array type.
* Remote objects should cheat devtools.
* Support cross-process callbacks.
