Remember when a variable has been expanded/unexpanded in the debugger.

runtime/observatory/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;
 
 class Notification {
   Notification.fromEvent(this.event);
   Notification.fromException(this.exception, this.stacktrace);
 
@@ skipping 208 matching lines @@
   loadCrashDump(Map crashDump) {
     this.vm = new FakeVM(crashDump['result']);
     app.locationManager.go('#/vm');
   }
 
   void handleException(e, st) {
     // TODO(turnidge): Report this failure via analytics.
     Logger.root.warning('Caught exception: ${e}\n${st}');
     notifications.add(new Notification.fromException(e, st));
   }
+
+  // This map keeps track of which curly-blocks have been expanded by the user.
+  Map<String,bool> expansions = {};
 }