[snapshot] full setup delegate should also be able to deserialize.

src/snapshot/deserializer.cc

Index: src/snapshot/deserializer.cc
diff --git a/src/snapshot/deserializer.cc b/src/snapshot/deserializer.cc
index 5656dee3bc1650ac2a3ebeb4ba383eee88738bbf..5c4671c26920fabb5002f40d002a51fe35654842 100644
--- a/src/snapshot/deserializer.cc
+++ b/src/snapshot/deserializer.cc
@@ -92,6 +92,8 @@ void Deserializer::Deserialize(Isolate* isolate) {
   DCHECK(isolate_->handle_scope_implementer()->blocks()->is_empty());
   // Partial snapshot cache is not yet populated.
   DCHECK(isolate_->partial_snapshot_cache()->is_empty());
+  // Builtins are not yet created.
+  DCHECK(!isolate_->builtins()->is_initialized());
 
   {
     DisallowHeapAllocation no_gc;
@@ -121,6 +123,8 @@ void Deserializer::Deserialize(Isolate* isolate) {
   LOG_CODE_EVENT(isolate_, LogCodeObjects());
   LOG_CODE_EVENT(isolate_, LogBytecodeHandlers());
   LOG_CODE_EVENT(isolate_, LogCompiledFunctions());
+
+  isolate_->builtins()->MarkInitialized();
 }
 
 MaybeHandle<Object> Deserializer::DeserializePartial(