issue #20803: stopped navigator from obtaining a lock on a new object

The code in navigator had a bad side effect if the list model was the same as editable model. It would obtain a lock on the editable model, which I think was an unintentional effect in that corner case. Moreover, the list.js modelChanged function did the same thing. So I just deleted the navigator code.

I also made some code in workspace.js more properly asynchronous.