Respect custom chunk size in RO serializer

Bug: v8:9533
Change-Id: Ida93a4a6dd5d25e78bb2bc113b869bc01cd7a650
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2043808
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66681}

src/snapshot/read-only-serializer.cc

@@ -19,6 +19,7 @@ namespace internal {
 ReadOnlySerializer::ReadOnlySerializer(Isolate* isolate)
     : RootsSerializer(isolate, RootIndex::kFirstReadOnlyRoot) {
   STATIC_ASSERT(RootIndex::kFirstReadOnlyRoot == RootIndex::kFirstRoot);
+  allocator()->UseCustomChunkSize(FLAG_serialization_chunk_size);
 }
 
 ReadOnlySerializer::~ReadOnlySerializer() {

src/snapshot/startup-serializer.cc

@@ -23,6 +23,7 @@ StartupSerializer::StartupSerializer(Isolate* isolate,
                                      ReadOnlySerializer* read_only_serializer)
     : RootsSerializer(isolate, RootIndex::kFirstStrongRoot),
       read_only_serializer_(read_only_serializer) {
+  allocator()->UseCustomChunkSize(FLAG_serialization_chunk_size);
   InitializeCodeAddressMap();
 }