Serialize all external strings except for native source code strings.

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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 2504 matching lines @@
         AllocationResult allocation = AllocateMap(entry.type, entry.size);
         if (!allocation.To(&obj)) return false;
       }
       // Mark cons string maps as unstable, because their objects can change
       // maps during GC.
       Map* map = Map::cast(obj);
       if (StringShape(entry.type).IsCons()) map->mark_unstable();
       roots_[entry.index] = map;
     }
 
+    {  // Create a separate external one byte string map for native sources.
+      AllocationResult allocation = AllocateMap(EXTERNAL_ONE_BYTE_STRING_TYPE,
+                                                ExternalOneByteString::kSize);
+      if (!allocation.To(&obj)) return false;
+      set_native_source_string_map(Map::cast(obj));
+    }
+
     ALLOCATE_VARSIZE_MAP(STRING_TYPE, undetectable_string)
     undetectable_string_map()->set_is_undetectable();
 
     ALLOCATE_VARSIZE_MAP(ONE_BYTE_STRING_TYPE, undetectable_one_byte_string);
     undetectable_one_byte_string_map()->set_is_undetectable();
 
     ALLOCATE_VARSIZE_MAP(FIXED_DOUBLE_ARRAY_TYPE, fixed_double_array)
     ALLOCATE_VARSIZE_MAP(BYTE_ARRAY_TYPE, byte_array)
     ALLOCATE_VARSIZE_MAP(FREE_SPACE_TYPE, free_space)
 
@@ skipping 3611 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal