[heap] Prevent direct access to ExternalStringTable.

src/extensions/externalize-string-extension.cc

 // Copyright 2010 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/extensions/externalize-string-extension.h"
 
 #include "src/api.h"
 #include "src/handles.h"
 #include "src/isolate.h"
 
@@ skipping 80 matching lines @@
     return;
   }
   if (string->IsOneByteRepresentation() && !force_two_byte) {
     uint8_t* data = new uint8_t[string->length()];
     String::WriteToFlat(*string, data, 0, string->length());
     SimpleOneByteStringResource* resource = new SimpleOneByteStringResource(
         reinterpret_cast<char*>(data), string->length());
     result = string->MakeExternal(resource);
     if (result) {
       i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
-      isolate->heap()->external_string_table()->AddString(*string);
+      isolate->heap()->RegisterExternalString(*string);
     }
     if (!result) delete resource;
   } else {
     uc16* data = new uc16[string->length()];
     String::WriteToFlat(*string, data, 0, string->length());
     SimpleTwoByteStringResource* resource = new SimpleTwoByteStringResource(
         data, string->length());
     result = string->MakeExternal(resource);
     if (result) {
       i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
-      isolate->heap()->external_string_table()->AddString(*string);
+      isolate->heap()->RegisterExternalString(*string);
     }
     if (!result) delete resource;
   }
   if (!result) {
     args.GetIsolate()->ThrowException(
         v8::String::NewFromUtf8(args.GetIsolate(),
                                 "externalizeString() failed.",
                                 NewStringType::kNormal).ToLocalChecked());
     return;
   }
@@ skipping 10 matching lines @@
             NewStringType::kNormal).ToLocalChecked());
     return;
   }
   bool is_one_byte =
       Utils::OpenHandle(*args[0].As<v8::String>())->IsOneByteRepresentation();
   args.GetReturnValue().Set(is_one_byte);
 }
 
 }  // namespace internal
 }  // namespace v8