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..c8d223a882c24e53c400c527f2bad069132066f9 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -2224,21 +2224,6 @@ 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;