VM: Fix --no-use-field-guards.

runtime/vm/raw_object_snapshot.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
@@ skipping 837 matching lines @@
   ASSERT((kind == Snapshot::kScript) || (kind == Snapshot::kFull));
 
   // Allocate field object.
   Field& field = Field::ZoneHandle(reader->zone(), NEW_OBJECT(Field));
   reader->AddBackRef(object_id, &field, kIsDeserialized);
 
   // Set all non object fields.
   if (reader->snapshot_code()) {
     field.set_token_pos(TokenPosition::kNoSource);
     ASSERT(!FLAG_use_field_guards);
-    field.set_guarded_cid(kDynamicCid);
-    field.set_is_nullable(true);
   } else {
     field.set_token_pos(
         TokenPosition::SnapshotDecode(reader->Read<int32_t>()));
     field.set_guarded_cid(reader->Read<int32_t>());
     field.set_is_nullable(reader->Read<int32_t>());
   }
   field.set_kind_bits(reader->Read<uint8_t>());
 
   // Set all the object fields.
   RawObject** toobj = reader->snapshot_code()
       ? field.raw()->to_precompiled_snapshot()
       : field.raw()->to();
   READ_OBJECT_FIELDS(field,
                      field.raw()->from(), toobj,
                      kAsReference);
 
-  if (reader->snapshot_code()) {
-    ASSERT(!FLAG_use_field_guards);
+  if (!FLAG_use_field_guards) {
+    field.set_guarded_cid(kDynamicCid);
+    field.set_is_nullable(true);
     field.set_guarded_list_length(Field::kNoFixedLength);
     field.set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
   } else {
     field.InitializeGuardedListLengthInObjectOffset();
   }
 
   return field.raw();
 }
 
 
@@ skipping 2765 matching lines @@
     // We do not allow objects with native fields in an isolate message.
     writer->SetWriteException(Exceptions::kArgument,
                               "Illegal argument in isolate message"
                               " : (object is a UserTag)");
   } else {
     UNREACHABLE();
   }
 }
 
 }  // namespace dart