Add some more categories for V8.TodoMVC to see what keeps us non-idle

tools/perf/page_sets/todomvc.py

Index: tools/perf/page_sets/todomvc.py
diff --git a/tools/perf/page_sets/todomvc.py b/tools/perf/page_sets/todomvc.py
index 4f095ecf29f153fe2064930873207a57a04740df..115b1a9cb4ad800e840b35865994e1573af1fddf 100644
--- a/tools/perf/page_sets/todomvc.py
+++ b/tools/perf/page_sets/todomvc.py
@@ -39,10 +39,13 @@ class TodoMVCPage(page_module.Page):
         """
         this.becameIdle = false;
         this.idleCallback = function(deadline) {
-            if (deadline.timeRemaining() > 20)
+            let idletime = deadline.timeRemaining();
+            console.time("time remaining: " + idletime);
+            if (idletime > 20)
                 this.becameIdle = true;
             else
                 requestIdleCallback(this.idleCallback);
+            console.timeEnd("time remaining: " + idletime);
         };
         requestIdleCallback(this.idleCallback);
         """