Experimental: use register allocation in the code for keyed property

src/register-allocator-ia32.h

 // Copyright 2008 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 52 matching lines @@
   // The copy constructor and assignment operators could each create a new
   // register reference.
   Result(const Result& other) {
     other.CopyTo(this);
   }
 
   Result& operator=(const Result& other) {
     if (this != &other) {
       Unuse();
       other.CopyTo(this);
-      // other.Unuse();
     }
     return *this;
   }
 
   ~Result() { Unuse(); }
 
   void Unuse();
 
   Type type() const { return type_; }
 
@@ skipping 138 matching lines @@
   }
 
  private:
   CodeGenerator* cgen_;
   RegisterFile registers_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_REGISTER_ALLOCATOR_IA32_H_