Change heuristic to determine which fields contain modifieable double boxes: do it if field was ini…

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 7211 matching lines @@
   result.set_name(name);
   result.set_is_static(is_static);
   if (is_static) {
     result.set_value(Object::null_instance());
   } else {
     result.SetOffset(0);
   }
   result.set_is_final(is_final);
   result.set_is_const(is_const);
   result.set_is_synthetic(is_synthetic);
+  result.set_is_double_initialized(false);
   result.set_owner(owner);
   result.set_token_pos(token_pos);
   result.set_has_initializer(false);
   result.set_initializer(Function::Handle());
   result.set_is_unboxing_candidate(true);
   result.set_guarded_cid(FLAG_use_field_guards ? kIllegalCid : kDynamicCid);
   result.set_is_nullable(FLAG_use_field_guards ? false : true);
   result.set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
   // Presently, we only attempt to remember the list length for final fields.
   if (is_final && FLAG_use_field_guards) {
@@ skipping 14100 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart