[keys] adding fast-path for dict-mode objects with own keys only

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 8377 matching lines @@
 
 
 Handle<FixedArray> JSObject::GetEnumPropertyKeys(Handle<JSObject> object) {
   Isolate* isolate = object->GetIsolate();
   if (object->HasFastProperties()) {
     return GetFastEnumPropertyKeys(isolate, object);
   } else if (object->IsJSGlobalObject()) {
     Handle<GlobalDictionary> dictionary(object->global_dictionary());
     int length = dictionary->NumberOfEnumElements();
     if (length == 0) {
-      return Handle<FixedArray>(isolate->heap()->empty_fixed_array());
+      return isolate->factory()->empty_fixed_array();
     }
     Handle<FixedArray> storage = isolate->factory()->NewFixedArray(length);
     dictionary->CopyEnumKeysTo(*storage);
     return storage;
   } else {
     Handle<NameDictionary> dictionary(object->property_dictionary());
     int length = dictionary->NumberOfEnumElements();
     if (length == 0) {
-      return Handle<FixedArray>(isolate->heap()->empty_fixed_array());
+      return isolate->factory()->empty_fixed_array();
     }
     Handle<FixedArray> storage = isolate->factory()->NewFixedArray(length);
     dictionary->CopyEnumKeysTo(*storage);
     return storage;
   }
 }
 
 
 enum IndexedOrNamed { kIndexed, kNamed };
 
@@ skipping 11342 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