Preserve order of fields when doing slow-to-fast object migration.

src/objects.h

 // Copyright 2012 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 3564 matching lines @@
                        Handle<Object> key,
                        Handle<Object> value,
                        PropertyDetails details);
 
   MUST_USE_RESULT static Handle<Derived> Add(
       Handle<Derived> dictionary,
       Key key,
       Handle<Object> value,
       PropertyDetails details);
 
+  // Returns iteration indices array for the |dictionary|.
+  // Values are direct indices in the |HashTable| array.
+  static Handle<FixedArray> BuildIterationIndicesArray(
+      Handle<Derived> dictionary);
+
  protected:
   // Generic at put operation.
   MUST_USE_RESULT static Handle<Derived> AtPut(
       Handle<Derived> dictionary,
       Key key,
       Handle<Object> value);
 
   // Add entry to dictionary.
   static void AddEntry(
       Handle<Derived> dictionary,
       Key key,
       Handle<Object> value,
       PropertyDetails details,
       uint32_t hash);
 
   // Generate new enumeration indices to avoid enumeration index overflow.
-  static void GenerateNewEnumerationIndices(Handle<Derived> dictionary);
+  // Returns iteration indices array for the |dictionary|.
+  static Handle<FixedArray> GenerateNewEnumerationIndices(
+      Handle<Derived> dictionary);
   static const int kMaxNumberKeyIndex = DerivedHashTable::kPrefixStartIndex;
   static const int kNextEnumerationIndexIndex = kMaxNumberKeyIndex + 1;
 };
 
 
 class NameDictionaryShape : public BaseShape<Handle<Name> > {
  public:
   static inline bool IsMatch(Handle<Name> key, Object* other);
   static inline uint32_t Hash(Handle<Name> key);
   static inline uint32_t HashForObject(Handle<Name> key, Object* object);
   static inline Handle<Object> AsHandle(Isolate* isolate, Handle<Name> key);
   static const int kPrefixSize = 2;
   static const int kEntrySize = 3;
   static const bool kIsEnumerable = true;
 };
 
 
 class NameDictionary: public Dictionary<NameDictionary,
                                         NameDictionaryShape,
                                         Handle<Name> > {
   typedef Dictionary<
       NameDictionary, NameDictionaryShape, Handle<Name> > DerivedDictionary;
 
  public:
   DECLARE_CAST(NameDictionary)
 
   // Copies enumerable keys to preallocated fixed array.
   void CopyEnumKeysTo(FixedArray* storage);
-  inline static void DoGenerateNewEnumerationIndices(
+  inline static Handle<FixedArray> DoGenerateNewEnumerationIndices(
       Handle<NameDictionary> dictionary);
 
   // Find entry for key, otherwise return kNotFound. Optimized version of
   // HashTable::FindEntry.
   int FindEntry(Handle<Name> key);
 };
 
 
 class NumberDictionaryShape : public BaseShape<uint32_t> {
  public:
@@ skipping 7200 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_