[heap] Fix a missing write barrier in Heap::Allocate.

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include <unordered_map>
 #include <unordered_set>
 
 #include "src/accessors.h"
@@ skipping 3463 matching lines @@
                                 AllocationSite* allocation_site) {
   DCHECK(gc_state_ == NOT_IN_GC);
   DCHECK(map->instance_type() != MAP_TYPE);
   int size = map->instance_size();
   if (allocation_site != NULL) {
     size += AllocationMemento::kSize;
   }
   HeapObject* result = nullptr;
   AllocationResult allocation = AllocateRaw(size, space);
   if (!allocation.To(&result)) return allocation;
-  // No need for write barrier since object is white and map is in old space.
-  result->set_map_after_allocation(map, SKIP_WRITE_BARRIER);
+  // New space objects are allocated white.
+  WriteBarrierMode write_barrier_mode =
+      space == NEW_SPACE ? SKIP_WRITE_BARRIER : UPDATE_WRITE_BARRIER;
+  result->set_map_after_allocation(map, write_barrier_mode);
   if (allocation_site != NULL) {
     AllocationMemento* alloc_memento = reinterpret_cast<AllocationMemento*>(
         reinterpret_cast<Address>(result) + map->instance_size());
     InitializeAllocationMemento(alloc_memento, allocation_site);
   }
   return result;
 }
 
 
 void Heap::InitializeJSObjectFromMap(JSObject* obj, FixedArray* properties,
@@ skipping 3076 matching lines @@
     case LO_SPACE:
       return "LO_SPACE";
     default:
       UNREACHABLE();
   }
   return NULL;
 }
 
 }  // namespace internal
 }  // namespace v8