[snapshot] make snapshot sink a non-dynamic member of the serializer.

src/snapshot/partial-serializer.h

Index: src/snapshot/partial-serializer.h
diff --git a/src/snapshot/partial-serializer.h b/src/snapshot/partial-serializer.h
index 83154b2c8c853a18d9ef59388a4c38d44cd4333e..1d4ce2ba20d4b1f5584c9e987bba2cdbf6b19a41 100644
--- a/src/snapshot/partial-serializer.h
+++ b/src/snapshot/partial-serializer.h
@@ -13,8 +13,7 @@ namespace internal {
 
 class PartialSerializer : public Serializer {
  public:
-  PartialSerializer(Isolate* isolate, Serializer* startup_snapshot_serializer,
-                    SnapshotByteSink* sink);
+  PartialSerializer(Isolate* isolate, Serializer* startup_snapshot_serializer);
 
   ~PartialSerializer() override;