Do not SortUniq store buffer before a regular iteration.

src/store-buffer.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 80 matching lines @@
 
   static StoreBufferMode store_buffer_mode() { return store_buffer_mode_; }
   static inline void set_store_buffer_mode(StoreBufferMode mode);
   static bool old_buffer_is_sorted() { return old_buffer_is_sorted_; }
 
   // Goes through the store buffer removing pointers to things that have
   // been promoted.  Rebuilds the store buffer completely if it overflowed.
   static void SortUniq();
   static void Verify();
 
+  static void PrepareForIteration();
+
 #ifdef DEBUG
   static void Clean();
   // Slow, for asserts only.
   static bool CellIsInStoreBuffer(Address cell);
 #endif
 
  private:
   // The store buffer is divided up into a new buffer that is constantly being
   // filled by mutator activity and an old buffer that is filled with the data
   // from the new buffer after compression.
@@ skipping 52 matching lines @@
     StoreBuffer::may_move_store_buffer_entries_ = stored_state_;
   }
 
  private:
   bool stored_state_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_WRITE_BARRIER_H_