Use the incremental root marking visitor for overapproximating the weak closure

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 29cf00e9757922789a908ccf24080fd296db8636..ab77377ddc2b92bcb1792d19bdd2027fa358a36f 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -1985,7 +1985,8 @@ void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) {
 }
 
 
-void MarkCompactCollector::MarkImplicitRefGroups() {
+void MarkCompactCollector::MarkImplicitRefGroups(
+    MarkObjectFunction mark_object) {
   List<ImplicitRefGroup*>* ref_groups =
       isolate()->global_handles()->implicit_ref_groups();
 
@@ -2003,9 +2004,7 @@ void MarkCompactCollector::MarkImplicitRefGroups() {
     // A parent object is marked, so mark all child heap objects.
     for (size_t j = 0; j < entry->length; ++j) {
       if ((*children[j])->IsHeapObject()) {
-        HeapObject* child = HeapObject::cast(*children[j]);
-        MarkBit mark = Marking::MarkBitFrom(child);
-        MarkObject(child, mark);
+        mark_object(heap(), HeapObject::cast(*children[j]));
       }
     }
 
@@ -2104,7 +2103,7 @@ void MarkCompactCollector::ProcessEphemeralMarking(
     if (!only_process_harmony_weak_collections) {
       isolate()->global_handles()->IterateObjectGroups(
           visitor, &IsUnmarkedHeapObjectWithHeap);
-      MarkImplicitRefGroups();
+      MarkImplicitRefGroups(&MarkCompactMarkingVisitor::MarkObject);
     }
     ProcessWeakCollections();
     work_to_do = !marking_deque_.IsEmpty();
@@ -2224,21 +2223,6 @@ void MarkCompactCollector::UncommitMarkingDeque() {
 }
 
 
-void MarkCompactCollector::OverApproximateWeakClosure() {
-  GCTracer::Scope gc_scope(heap()->tracer(),
-                           GCTracer::Scope::MC_INCREMENTAL_WEAKCLOSURE);
-
-  RootMarkingVisitor root_visitor(heap());
-  isolate()->global_handles()->IterateObjectGroups(
-      &root_visitor, &IsUnmarkedHeapObjectWithHeap);
-  MarkImplicitRefGroups();
-
-  // Remove object groups after marking phase.
-  heap()->isolate()->global_handles()->RemoveObjectGroups();
-  heap()->isolate()->global_handles()->RemoveImplicitRefGroups();
-}
-
-
 void MarkCompactCollector::MarkLiveObjects() {
   GCTracer::Scope gc_scope(heap()->tracer(), GCTracer::Scope::MC_MARK);
   double start_time = 0.0;