Collect type feedback for fields.

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 724e895f5e386aee4d35ce5dfaaac01dc32b667e..590e629f738e0526ac9e59bb9f06a086ba2a75aa 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -769,6 +769,8 @@ RawField* Field::ReadFrom(SnapshotReader* reader,
 
   // Set all non object fields.
   field.set_token_pos(reader->ReadIntptrValue());
+  field.set_guarded_cid(reader->ReadIntptrValue());
+  field.set_is_nullable(reader->ReadIntptrValue());
   field.set_kind_bits(reader->Read<uint8_t>());
 
   // Set all the object fields.
@@ -799,6 +801,8 @@ void RawField::WriteTo(SnapshotWriter* writer,
 
   // Write out all the non object fields.
   writer->WriteIntptrValue(ptr()->token_pos_);
+  writer->WriteIntptrValue(ptr()->guarded_cid_);
+  writer->WriteIntptrValue(ptr()->is_nullable_);
   writer->Write<uint8_t>(ptr()->kind_bits_);
 
   // Write out all the object pointer fields.