cf410d0 broke thread sorting by interfering with the (admittedly
arcane) sort apparatus.

There is a scope.watch in the AppController which is responsible for
filling the `predicate` field of the `sort` object when the `name` field
changes. In order for this to work, the controllers in child scopes
(namely StreamController or WidgetController) need to modify the `name`
property of the `sort` object in the parent scope, via prototypal
inheritance, rather than replacing the entire `sort` object.