'Share' menu shares URL without a scheme and host name

The 'Share' menu shares URLs to documents. These URLs should be fully qualified, i.e. include a scheme and host name. However, they only consist of an absolute path.

Steps to reproduce:
1. open a document, i.e. 'Hippo Go Green/Events/2013/03/Future Build 2012 - The Eco Event in California'
2. select 'Share -> Facebook'

Expected: the URL is fully qualified (http://localhost:8080/site/events/2013/03/future-build-2012-–-the-eco-event-in-california.html)

Actual: the URL only consist of a path; in case of Facebook, the host www.facebook.com is prepended, so you end up sharing the URL 'http://www.facebook.com/site/events/2013/03/future-build-2012-–-the-eco-event-in-california.html'