Auto expand first profiler row when it has no siblings

runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart

Index: runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart
diff --git a/runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart b/runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart
index dafa994095edc37b38a4da75f6a85f73b838b570..1c3ef11d23b2610e7771ff36bc2adcdc144300a4 100644
--- a/runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart
+++ b/runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart
@@ -163,6 +163,10 @@ class IsolateProfileElement extends ObservatoryElement {
     } catch (e, stackTrace) {
       Logger.root.warning('_buildStackTree', e, stackTrace);
     }
+    // Check if we only have one node at the root and expand it.
+    if (tree.rows.length == 1) {
+      tree.toggle(0);
+    }
     notifyPropertyChange(#tree, null, tree);
   }