Implemented lazy sweeping of new space.

src/store-buffer-inl.h

Index: src/store-buffer-inl.h
diff --git a/src/store-buffer-inl.h b/src/store-buffer-inl.h
index dd65cbcc9c5764c0b9d7c1544463f754c372bc7b..bb386dbacf94359961727725b14f36639a425596 100644
--- a/src/store-buffer-inl.h
+++ b/src/store-buffer-inl.h
@@ -74,6 +74,14 @@ void StoreBuffer::EnterDirectlyIntoStoreBuffer(Address addr) {
 }
 
 
+void StoreBuffer::ClearDeadObject(HeapObject* object) {
+  Address& map_field = Memory::Address_at(object->address());
+  if (heap_->map_space()->Contains(map_field)) {
+    map_field = NULL;
+  }
+}
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_STORE_BUFFER_INL_H_