[runtime] Stop cloning AccessorInfo, just rely on PropertyAttributes for readonly.

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 5186 matching lines @@
   DCHECK(!it.IsFound());
   DCHECK(object->map()->is_extensible() ||
          it.isolate()->IsInternallyUsedPropertyName(name));
 #endif
   CHECK(AddDataProperty(&it, value, attributes, THROW_ON_ERROR,
                         CERTAINLY_NOT_STORE_FROM_KEYED)
             .IsJust());
 }
 
 
-// static
-void AccessorInfo::ClearSetter(Handle<AccessorInfo> info) {
-  Handle<Object> object = v8::FromCData(info->GetIsolate(), nullptr);
-  info->set_setter(*object);
-}
-
-
 // Reconfigures a property to a data property with attributes, even if it is not
 // reconfigurable.
 // Requires a LookupIterator that does not look at the prototype chain beyond
 // hidden prototypes.
 MaybeHandle<Object> JSObject::DefineOwnPropertyIgnoreAttributes(
     LookupIterator* it, Handle<Object> value, PropertyAttributes attributes,
     AccessorInfoHandling handling) {
   MAYBE_RETURN_NULL(DefineOwnPropertyIgnoreAttributes(
       it, value, attributes, THROW_ON_ERROR, handling));
   return value;
@@ skipping 48 matching lines @@
           // Ensure the context isn't changed after calling into accessors.
           AssertNoContextChange ncc(it->isolate());
 
           Maybe<bool> result =
               JSObject::SetPropertyWithAccessor(it, value, should_throw);
           if (result.IsNothing() || !result.FromJust()) return result;
 
           if (details.attributes() == attributes) return Just(true);
 
           // Reconfigure the accessor if attributes mismatch.
-          Handle<AccessorInfo> new_data = Accessors::CloneAccessor(
-              it->isolate(), Handle<AccessorInfo>::cast(accessors));
-          new_data->set_property_attributes(attributes);
-          // By clearing the setter we don't have to introduce a lookup to
-          // the setter, simply make it unavailable to reflect the
-          // attributes.
-          if (attributes & READ_ONLY) AccessorInfo::ClearSetter(new_data);
-
-          it->TransitionToAccessorPair(new_data, attributes);
+          it->TransitionToAccessorPair(accessors, attributes);
         } else {
           it->ReconfigureDataProperty(value, attributes);
         }
 
         if (is_observed) {
           RETURN_ON_EXCEPTION_VALUE(
               it->isolate(),
               EnqueueChangeRecord(object, "reconfigure", it->GetName(),
                                   it->factory()->the_hole_value()),
               Nothing<bool>());
@@ skipping 14384 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8