Move Maps' back pointers from "transitions" to "constructor" field

src/runtime/runtime-regexp.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/arguments.h"
 #include "src/jsregexp-inl.h"
 #include "src/jsregexp.h"
 #include "src/runtime/runtime-utils.h"
@@ skipping 848 matching lines @@
         isolate, NewSyntaxError("invalid_regexp_flags", args));
   }
 
   Handle<Object> global = factory->ToBoolean(flags.is_global());
   Handle<Object> ignore_case = factory->ToBoolean(flags.is_ignore_case());
   Handle<Object> multiline = factory->ToBoolean(flags.is_multiline());
   Handle<Object> sticky = factory->ToBoolean(flags.is_sticky());
   Handle<Object> unicode = factory->ToBoolean(flags.is_unicode());
 
   Map* map = regexp->map();
-  Object* constructor = map->constructor();
+  Object* constructor = map->GetConstructor();
   if (!FLAG_harmony_regexps && !FLAG_harmony_unicode_regexps &&
       constructor->IsJSFunction() &&
       JSFunction::cast(constructor)->initial_map() == map) {
     // If we still have the original map, set in-object properties directly.
     // Both true and false are immovable immortal objects so no need for write
     // barrier.
     regexp->InObjectPropertyAtPut(JSRegExp::kGlobalFieldIndex, *global,
                                   SKIP_WRITE_BARRIER);
     regexp->InObjectPropertyAtPut(JSRegExp::kIgnoreCaseFieldIndex, *ignore_case,
                                   SKIP_WRITE_BARRIER);
@@ skipping 243 matching lines @@
 
 
 RUNTIME_FUNCTION(RuntimeReference_IsRegExp) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(Object, obj, 0);
   return isolate->heap()->ToBoolean(obj->IsJSRegExp());
 }
 }
 }  // namespace v8::internal