Fix the types used in bit fields.

vm/raw_object_snapshot.cc

Index: vm/raw_object_snapshot.cc
===================================================================
--- vm/raw_object_snapshot.cc	(revision 12729)
+++ vm/raw_object_snapshot.cc	(working copy)
@@ -536,7 +536,7 @@
   func.set_num_fixed_parameters(reader->ReadIntptrValue());
   func.set_num_optional_parameters(reader->ReadIntptrValue());
   func.set_deoptimization_counter(reader->ReadIntptrValue());
-  func.set_kind_tag(reader->ReadIntptrValue());
+  func.set_kind_tag(reader->Read<uint16_t>());
 
   // Set all the object fields.
   // TODO(5411462): Need to assert No GC can happen here, even though
@@ -571,7 +571,7 @@
   writer->WriteIntptrValue(ptr()->num_fixed_parameters_);
   writer->WriteIntptrValue(ptr()->num_optional_parameters_);
   writer->WriteIntptrValue(ptr()->deoptimization_counter_);
-  writer->WriteIntptrValue(ptr()->kind_tag_);
+  writer->Write<uint16_t>(ptr()->kind_tag_);
 
   // Write out all the object pointer fields.
   SnapshotWriterVisitor visitor(writer);
@@ -626,7 +626,7 @@
 
   // Write out all the non object fields.
   writer->WriteIntptrValue(ptr()->token_pos_);
-  writer->WriteIntptrValue(ptr()->kind_bits_);
+  writer->Write<uint8_t>(ptr()->kind_bits_);
 
   // Write out all the object pointer fields.
   SnapshotWriterVisitor visitor(writer);