Serializer: serialize internal references via object visitor.

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index bf3572dc548c3e2ee99867471a5a89840294c8ca..56c99fd43f4a6bc915bfecaa4b67b7152e4b0fa4 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -570,6 +570,10 @@ class Assembler : public AssemblerBase {
     set_target_address_at(instruction_payload, code, target);
   }
 
+  // This sets the internal reference at the pc.
+  inline static void deserialization_set_target_internal_reference_at(
+      Address instruction, Address target);
+
   static inline RelocInfo::Mode RelocInfoNone() {
     if (kPointerSize == kInt64Size) {
       return RelocInfo::NONE64;