Never hchange nan-hole to hole or hole to nan-hole.

src/lithium.h

 // Copyright 2012 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 781 matching lines @@
   ZoneList<LPointerMap*> pointer_maps_;
   ZoneList<Handle<JSFunction> > inlined_closures_;
 };
 
 
 int ElementsKindToShiftSize(ElementsKind elements_kind);
 int StackSlotOffset(int index);
 
 enum NumberUntagDMode {
   NUMBER_CANDIDATE_IS_SMI,
-  NUMBER_CANDIDATE_IS_ANY_TAGGED,
-  NUMBER_CANDIDATE_IS_ANY_TAGGED_CONVERT_HOLE
+  NUMBER_CANDIDATE_IS_ANY_TAGGED
 };
 
 
 class LPhase : public CompilationPhase {
  public:
   LPhase(const char* name, LChunk* chunk)
       : CompilationPhase(name, chunk->info()),
         chunk_(chunk) { }
   ~LPhase();
 
  private:
   LChunk* chunk_;
 
   DISALLOW_COPY_AND_ASSIGN(LPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LITHIUM_H_