Fix filemodel dispose and test

src/filebrowser/model.ts

@@ -118,6 +118,7 @@ class FileBrowserModel implements IDisposable, IPathTracker {
     }
     clearTimeout(this._timeoutId);
     clearInterval(this._refreshId);
+    clearTimeout(this._blackoutId);
     this._model = null;
     this._sessions.clear();
     this._items.clear();

test/src/filebrowser/model.spec.ts

@@ -163,7 +163,7 @@ describe('filebrowser/model', () => {
           session = s;
           return model.cd();
         }).then(() => {
-          expect(model.sessions().next).to.be.ok();
+          expect(model.sessions().next()).to.be.ok();
           return session.shutdown();
         }).then(() => {
           done();