[serializer] do not cache resource data pointer for native source.

src/bootstrapper.cc

 // Copyright 2014 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/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 18 matching lines @@
 
 template <class Source>
 Handle<String> Bootstrapper::SourceLookup(int index) {
   DCHECK(0 <= index && index < Source::GetBuiltinsCount());
   Heap* heap = isolate_->heap();
   if (Source::GetSourceCache(heap)->get(index)->IsUndefined()) {
     // We can use external strings for the natives.
     Vector<const char> source = Source::GetScriptSource(index);
     NativesExternalStringResource* resource =
         new NativesExternalStringResource(source.start(), source.length());
-    // We do not expect this to throw an exception. Change this if it does.
-    Handle<String> source_code = isolate_->factory()
-                                     ->NewExternalStringFromOneByte(resource)
-                                     .ToHandleChecked();
+    Handle<ExternalOneByteString> source_code =
+        isolate_->factory()->NewNativeSourceString(resource);
     // Mark this external string with a special map.
-    source_code->set_map(isolate_->heap()->native_source_string_map());
+    DCHECK(source_code->is_short());
     Source::GetSourceCache(heap)->set(index, *source_code);
   }
   Handle<Object> cached_source(Source::GetSourceCache(heap)->get(index),
                                isolate_);
   return Handle<String>::cast(cached_source);
 }
 
 
 template Handle<String> Bootstrapper::SourceLookup<Natives>(int index);
 template Handle<String> Bootstrapper::SourceLookup<ExperimentalNatives>(
@@ skipping 3721 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8