[heap] Simplify clearing of normalized map caches.

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 3477261721b29ab74f192d10dc1a95ecb41631c1..a124fd3ba99609da4c61615103c1608a0358d507 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -153,7 +153,6 @@ class IncrementalMarkingMarkingVisitor
   static void Initialize() {
     StaticMarkingVisitor<IncrementalMarkingMarkingVisitor>::Initialize();
     table_.Register(kVisitFixedArray, &VisitFixedArrayIncremental);
-    table_.Register(kVisitNativeContext, &VisitNativeContextIncremental);
   }
 
   static const int kProgressBarScanningChunk = 32 * 1024;
@@ -199,26 +198,6 @@ class IncrementalMarkingMarkingVisitor
     }
   }
 
-  static void VisitNativeContextIncremental(Map* map, HeapObject* object) {
-    Context* context = Context::cast(object);
-
-    // We will mark cache black with a separate pass when we finish marking.
-    // Note that GC can happen when the context is not fully initialized,
-    // so the cache can be undefined.
-    Object* cache = context->get(Context::NORMALIZED_MAP_CACHE_INDEX);
-    if (!cache->IsUndefined(map->GetIsolate())) {
-      if (cache->IsHeapObject()) {
-        HeapObject* heap_obj = HeapObject::cast(cache);
-        // Mark the object grey if it is white, do not enque it into the marking
-        // deque.
-        if (ObjectMarking::IsWhite(heap_obj)) {
-          ObjectMarking::WhiteToGrey(heap_obj);
-        }
-      }
-    }
-    VisitNativeContext(map, context);
-  }
-
   INLINE(static void VisitPointer(Heap* heap, HeapObject* object, Object** p)) {
     Object* target = *p;
     if (target->IsHeapObject()) {