Allows unboxed doubles to be disabled.

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 6808 matching lines @@
   return Smi::Value(raw_ptr()->guarded_list_length_);
 }
 
 
 void Field::set_guarded_list_length(intptr_t list_length) const {
   raw_ptr()->guarded_list_length_ = Smi::New(list_length);
 }
 
 
 bool Field::IsUnboxedField() const {
-  bool valid_class = (guarded_cid() == kDoubleCid) ||
+  bool valid_class = (FlowGraphCompiler::SupportsUnboxedDoubles() &&
+                      (guarded_cid() == kDoubleCid)) ||
                      (FlowGraphCompiler::SupportsUnboxedSimd128() &&
                       (guarded_cid() == kFloat32x4Cid)) ||
                      (FlowGraphCompiler::SupportsUnboxedSimd128() &&
                       (guarded_cid() == kFloat64x2Cid));
   return is_unboxing_candidate() && !is_final() && !is_nullable() &&
          valid_class;
 }
 
 
 bool Field::IsPotentialUnboxedField() const {
@@ skipping 12005 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart