Refactor register allocator a little bit

src/x64/lithium-x64.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 2524 matching lines @@
   DECLARE_CONCRETE_INSTRUCTION(LoadFieldByIndex, "load-field-by-index")
 };
 
 
 class LChunkBuilder;
 class LPlatformChunk V8_FINAL : public LChunk {
  public:
   LPlatformChunk(CompilationInfo* info, HGraph* graph)
       : LChunk(info, graph) { }
 
-  int GetNextSpillIndex(bool is_double);
-  LOperand* GetNextSpillSlot(bool is_double);
+  int GetNextSpillIndex(RegisterKind kind);
+  LOperand* GetNextSpillSlot(RegisterKind kind);
 };
 
 
 class LChunkBuilder V8_FINAL BASE_EMBEDDED {
  public:
   LChunkBuilder(CompilationInfo* info, HGraph* graph, LAllocator* allocator)
       : chunk_(NULL),
         info_(info),
         graph_(graph),
         zone_(graph->zone()),
@@ skipping 160 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_