Final Observatory 1.5 fixes

runtime/bin/vmservice/client/lib/src/app/application.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of app;
 
 /// A [Pane] controls the user interface of Observatory. At any given time
 /// one pane will be the current pane. Panes are registered at startup.
 /// When the user navigates within the application, each pane is asked if it
 /// can handle the current location, the first pane to say yes, wins.
@@ skipping 29 matching lines @@
   void onInstall() {
     if (element == null) {
       /// Lazily create pane.
       element = new Element.tag('service-view');
     }
   }
 
   void visit(String url) {
     assert(element != null);
     assert(canVisit(url));
+    if (url == '') {
+      // Nothing requested.
+      return;
+    }
     /// Request url from VM and display it.
     app.vm.get(url).then((obj) {
       ServiceObjectViewElement pane = element;
       pane.object = obj;
     });
   }
 
   /// Catch all.
   bool canVisit(String url) => true;
 }
@@ skipping 137 matching lines @@
   }
 
   ObservatoryApplication(this.rootElement) :
       locationManager = new HashLocationManager(),
       vm = new HttpVM() {
     _initOnce();
   }
 }
 
 LocationManager location;