These are interim changes, for an approach i'm going to be replacing with a better one.  The issue is provisioning the combo root node using the respective content roots that, which this approach factors into directing the respective roots to layout sections of the combo root page. (Instead, it  will be much simpler to have them layout their own pages and then give the combo root copies of their rendered content.)
These are interim changes, for an approach i'm going to be replacing with a
better one.  The issue is provisioning the combo root node using the
respective content roots that, which this approach factors into directing
the respective roots to layout sections of the combo root page. (Instead,
it  will be much simpler to have them layout their own pages and then give
the combo root copies of their rendered content.)

This checkin involves complication of the ContentNode.prototype.visit()
method, in order to interweave alternative callback handlers.  (Instead, we
should use node-specific visit methods, and more explicit collaboration
between the different types of nodes, when called for.)

SpiderOak/so_client_html5,SpiderOak/so_client_html5