Clean some unuse code of unary negation

src/hydrogen.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 1789 matching lines @@
 #define INLINE_FUNCTION_GENERATOR_DECLARATION(Name, argc, ressize)      \
   void Generate##Name(CallRuntime* call);
 
   INLINE_FUNCTION_LIST(INLINE_FUNCTION_GENERATOR_DECLARATION)
   INLINE_RUNTIME_FUNCTION_LIST(INLINE_FUNCTION_GENERATOR_DECLARATION)
 #undef INLINE_FUNCTION_GENERATOR_DECLARATION
 
   void VisitDelete(UnaryOperation* expr);
   void VisitVoid(UnaryOperation* expr);
   void VisitTypeof(UnaryOperation* expr);
-  void VisitSub(UnaryOperation* expr);
   void VisitBitNot(UnaryOperation* expr);
   void VisitNot(UnaryOperation* expr);
 
   void VisitComma(BinaryOperation* expr);
   void VisitLogicalExpression(BinaryOperation* expr);
   void VisitArithmeticExpression(BinaryOperation* expr);
 
   bool PreProcessOsrEntry(IterationStatement* statement);
   void VisitLoopBody(IterationStatement* stmt,
                      HBasicBlock* loop_entry,
@@ skipping 505 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_