Revert "Improve hashCode for closure objects"

runtime/vm/clustered_snapshot.cc

Index: runtime/vm/clustered_snapshot.cc
diff --git a/runtime/vm/clustered_snapshot.cc b/runtime/vm/clustered_snapshot.cc
index 32be29aed3a38f7f6b249f0b2c2016ae9a888d50..609fd327af02c0f61ab372fc10e4ac9d190e05f8 100644
--- a/runtime/vm/clustered_snapshot.cc
+++ b/runtime/vm/clustered_snapshot.cc
@@ -764,6 +764,7 @@ class ClosureDataDeserializationCluster : public DeserializationCluster {
       data->ptr()->parent_function_ = static_cast<RawFunction*>(d->ReadRef());
       data->ptr()->signature_type_ = static_cast<RawType*>(d->ReadRef());
       data->ptr()->closure_ = static_cast<RawInstance*>(d->ReadRef());
+      data->ptr()->hash_ = Object::null();
     }
   }
 };