* Propagate referrer to new windows
Fixes#9205
* Rearrange -new-window event arguments for backwards-compatibility
* Plumb referrer policy through guest-window-manager
* Document the Referrer structure and its uses
* Add tests for referrer in new windows
* Docs nits
Previously we rely on the v8util.setDestructor to dereference the remote
objects in JavaScript, however as documented in V8, it is forbidden to
call V8 APIs in object's destructor (e.g. the weak callback), and doing
so would result in crashs.
This commit removes the JavaScript setDestructor method, and avoids
doing the dereference work with V8.
