Use the incremental root marking visitor for overapproximating the weak closure

src/heap/incremental-marking.cc

Index: src/heap/incremental-marking.cc
diff --git a/src/heap/incremental-marking.cc b/src/heap/incremental-marking.cc
index 76c05de6065be5da1c51e8a7f7f8894f1eed82fb..3a24114bea7d2dbef998a59756662b21b073bb06 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -777,7 +777,6 @@ void IncrementalMarking::OverApproximateWeakClosure() {
   if (FLAG_trace_incremental_marking) {
     PrintF("[IncrementalMarking] requesting weak closure overapproximation.\n");
   }
-  set_should_hurry(true);
   request_type_ = OVERAPPROXIMATION;
   heap_->isolate()->stack_guard()->RequestGC();
 }
@@ -1000,6 +999,11 @@ bool IncrementalMarking::IsIdleMarkingDelayCounterLimitReached() {
 }
 
 
+ObjectVisitor* IncrementalMarking::CreateRootMarkingVisitor() {
+  return new IncrementalMarkingRootMarkingVisitor(this);
+}
+
+
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }