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

src/heap/incremental-marking.h

Index: src/heap/incremental-marking.h
diff --git a/src/heap/incremental-marking.h b/src/heap/incremental-marking.h
index 21fdb2da3735b1cf5ff67f712ecc71e71a2c1c3f..231a27ac8400376cbdac55fa443760c27cc77238 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -53,6 +53,10 @@ class IncrementalMarking {
 
   inline bool IsComplete() { return state() == COMPLETE; }
 
+  inline bool IsReadyToOverApproximateWeakClosure() const {
+    return request_type_ == OVERAPPROXIMATION;
+  }
+
   GCRequestType request_type() const { return request_type_; }
 
   bool WorthActivating();
@@ -79,7 +83,7 @@ class IncrementalMarking {
 
   void Abort();
 
-  void OverApproximateWeakClosure();
+  void OverApproximateWeakClosure(CompletionAction action);
 
   void MarkingComplete(CompletionAction action);