Revert async changes.

runtime/vm/raw_object_snapshot.cc

Index: runtime/vm/raw_object_snapshot.cc
diff --git a/runtime/vm/raw_object_snapshot.cc b/runtime/vm/raw_object_snapshot.cc
index fa256569969fc9893b31d0859de9471ca2ecf995..94358f6f14bdbee67ae70f88e87c86eb1608b99f 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -698,7 +698,7 @@ RawFunction* Function::ReadFrom(SnapshotReader* reader,
   func.set_num_fixed_parameters(reader->Read<int16_t>());
   func.set_num_optional_parameters(reader->Read<int16_t>());
   func.set_deoptimization_counter(reader->Read<int16_t>());
-  func.set_kind_tag(reader->Read<uint32_t>());
+  func.set_kind_tag(reader->Read<uint16_t>());
   func.set_optimized_instruction_count(reader->Read<uint16_t>());
   func.set_optimized_call_site_count(reader->Read<uint16_t>());
 
@@ -739,7 +739,7 @@ void RawFunction::WriteTo(SnapshotWriter* writer,
   writer->Write<int16_t>(ptr()->num_fixed_parameters_);
   writer->Write<int16_t>(ptr()->num_optional_parameters_);
   writer->Write<int16_t>(ptr()->deoptimization_counter_);
-  writer->Write<uint32_t>(ptr()->kind_tag_);
+  writer->Write<uint16_t>(ptr()->kind_tag_);
   writer->Write<uint16_t>(ptr()->optimized_instruction_count_);
   writer->Write<uint16_t>(ptr()->optimized_call_site_count_);