Hook up over approximating the weak closure to the idle time handler

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 913ac13d43832494e2234c123e6e421e2074cc6e..e5c352c1252ee9ed48e3737ab4fb3dab63a92de3 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -4584,11 +4584,19 @@ void Heap::IdleMarkCompact(const char* message) {
 bool Heap::TryFinalizeIdleIncrementalMarking(
     double idle_time_in_ms, size_t size_of_objects,
     size_t final_incremental_mark_compact_speed_in_bytes_per_ms) {
-  if (incremental_marking()->IsComplete() ||
-      (mark_compact_collector_.marking_deque()->IsEmpty() &&
-       gc_idle_time_handler_.ShouldDoFinalIncrementalMarkCompact(
-           static_cast<size_t>(idle_time_in_ms), size_of_objects,
-           final_incremental_mark_compact_speed_in_bytes_per_ms))) {
+  if (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
+      (FLAG_overapproximate_weak_closure &&
+       mark_compact_collector_.marking_deque()->IsEmpty() &&
+       gc_idle_time_handler_.ShouldDoOverApproximateWeakClosure(
+           static_cast<size_t>(idle_time_in_ms)))) {
+    OverApproximateWeakClosure(
+        "Idle notification: overapproximate weak closure");
+    return true;
+  } else if (incremental_marking()->IsComplete() ||
+             (mark_compact_collector_.marking_deque()->IsEmpty() &&
+              gc_idle_time_handler_.ShouldDoFinalIncrementalMarkCompact(
+                  static_cast<size_t>(idle_time_in_ms), size_of_objects,
+                  final_incremental_mark_compact_speed_in_bytes_per_ms))) {
     CollectAllGarbage(kNoGCFlags, "idle notification: finalize incremental");
     return true;
   }