Change MergeTo code for virtual frames to use register indices.

src/virtual-frame.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 173 matching lines @@
         copied_(false),
         synced_(is_synced != NOT_SYNCED) {
     data_.handle_ = value.location();
   }
 
   void set_index(int new_index) {
     ASSERT(is_copy());
     data_.index_ = new_index;
   }
 
+  void set_reg(Register new_reg) {
+    ASSERT(is_register());
+    data_.reg_ = new_reg;
+  }
+
   friend class VirtualFrame;
 };
 
 
 } }  // namespace v8::internal
 
 #ifdef ARM
 #include "arm/virtual-frame-arm.h"
 #else  // ia32
 #include "ia32/virtual-frame-ia32.h"
 #endif
 
 #endif  // V8_VIRTUAL_FRAME_H_