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

src/factory.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/factory.h"
 
 #include "src/allocation-site-scopes.h"
 #include "src/base/bits.h"
 #include "src/conversions.h"
 #include "src/isolate-inl.h"
@@ skipping 1938 matching lines @@
   // context the JSProxy originated in. But that context isn't stored anywhere.
   Handle<Context> context(isolate()->native_context());
 
   // Functions require some minimal initialization.
   if (type == JS_FUNCTION_TYPE) {
     map->set_function_with_prototype(true);
     Handle<JSFunction> js_function = Handle<JSFunction>::cast(proxy);
     InitializeFunction(js_function, shared.ToHandleChecked(), context);
   } else {
     // Provide JSObjects with a constructor.
-    map->set_constructor(context->object_function());
+    map->SetConstructor(context->object_function());
   }
 }
 
 
 Handle<JSGlobalProxy> Factory::NewUninitializedJSGlobalProxy() {
   // Create an empty shell of a JSGlobalProxy that needs to be reinitialized
   // via ReinitializeJSGlobalProxy later.
   Handle<Map> map = NewMap(JS_GLOBAL_PROXY_TYPE, JSGlobalProxy::kSize);
   // Maintain invariant expected from any JSGlobalProxy.
   map->set_is_access_check_needed(true);
@@ skipping 362 matching lines @@
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 } }  // namespace v8::internal