[serializer] allow duplicate API external references.

test/cctest/test-serialize.cc

Index: test/cctest/test-serialize.cc
diff --git a/test/cctest/test-serialize.cc b/test/cctest/test-serialize.cc
index e7170206756927f865a6ba45aab48f6d4aa4ca66..247988255da605d036220b1152abfff414efd07d 100644
--- a/test/cctest/test-serialize.cc
+++ b/test/cctest/test-serialize.cc
@@ -1986,6 +1986,7 @@ intptr_t original_external_references[] = {
     reinterpret_cast<intptr_t>(&NamedPropertyGetterForSerialization),
     reinterpret_cast<intptr_t>(&AccessorForSerialization),
     reinterpret_cast<intptr_t>(&SerializedExtension::FunctionCallback),
+    reinterpret_cast<intptr_t>(&serialized_static_field),  // duplicate entry
     0};
 
 intptr_t replaced_external_references[] = {
@@ -1994,6 +1995,7 @@ intptr_t replaced_external_references[] = {
     reinterpret_cast<intptr_t>(&NamedPropertyGetterForSerialization),
     reinterpret_cast<intptr_t>(&AccessorForSerialization),
     reinterpret_cast<intptr_t>(&SerializedExtension::FunctionCallback),
+    reinterpret_cast<intptr_t>(&serialized_static_field),
     0};
 
 TEST(SnapshotCreatorExternalReferences) {