Update the navbar in the observatory

runtime/bin/vmservice/client/lib/src/observatory/model.dart

Index: runtime/bin/vmservice/client/lib/src/observatory/model.dart
diff --git a/runtime/bin/vmservice/client/lib/src/observatory/model.dart b/runtime/bin/vmservice/client/lib/src/observatory/model.dart
index 92652308bb6df57a72858a48e1d4b87e84dd6cb6..4d0545ae8daf7733c3e5db67dee6ad89262156ff 100644
--- a/runtime/bin/vmservice/client/lib/src/observatory/model.dart
+++ b/runtime/bin/vmservice/client/lib/src/observatory/model.dart
@@ -302,6 +302,7 @@ class ScriptLine extends Observable {
 class Script extends Observable {
   @observable String kind = null;
   @observable Map scriptRef = toObservable({});
+  @published String shortName;
   @observable Map libraryRef = toObservable({});
   @observable final List<ScriptLine> lines =
       toObservable(new List<ScriptLine>());
@@ -313,6 +314,7 @@ class Script extends Observable {
       'name': map['name'],
       'user_name': map['user_name']
     });
+    shortName = map['name'].substring(map['name'].lastIndexOf('/') + 1);
     libraryRef = toObservable(map['library']);
     kind = map['kind'];
     _processSource(map['source']);