Miscellaneous Observatory UI improvements

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 14391e1d0f0bc75cc0570184b5e67439869c6a88..3e7322e75108ffaf8f3931705ecf6baf954a1ecd 100644
--- a/runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart
+++ b/runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart
@@ -234,11 +234,17 @@ class IsolateProfileElement extends ObservatoryElement {
   }
 
   @observable void toggleExpanded(Event e, var detail, Element target) {
+    // We only want to expand a tree row if the target of the click is
+    // the table cell (passed in as target) or the span containing the
+    // expander symbol (#expand).
+    if ((e.target.id != 'expand') && (e.target != target)) {
+      // Target of click was not the expander span or the table cell.
+      return;
+    }
     var row = target.parent;
     if (row is TableRowElement) {
       // Subtract 1 to get 0 based indexing.
       tree.toggle(row.rowIndex - 1);
     }
   }
-
 }