Get rid of the unused native code StringAddStub.

src/mips/code-stubs-mips.h

 // Copyright 2011 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 102 matching lines @@
                                        Register character);
 
   static void GenerateHashGetHash(MacroAssembler* masm,
                                   Register hash);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
 };
 
 
-class StringAddStub: public PlatformCodeStub {
- public:
-  explicit StringAddStub(StringAddFlags flags) : flags_(flags) {}
-
- private:
-  Major MajorKey() { return StringAdd; }
-  int MinorKey() { return flags_; }
-
-  void Generate(MacroAssembler* masm);
-
-  void GenerateConvertArgument(MacroAssembler* masm,
-                               int stack_offset,
-                               Register arg,
-                               Register scratch1,
-                               Register scratch2,
-                               Register scratch3,
-                               Register scratch4,
-                               Label* slow);
-
-  void GenerateRegisterArgsPush(MacroAssembler* masm);
-  void GenerateRegisterArgsPop(MacroAssembler* masm);
-
-  const StringAddFlags flags_;
-};
-
-
 class SubStringStub: public PlatformCodeStub {
  public:
   SubStringStub() {}
 
  private:
   Major MajorKey() { return SubString; }
   int MinorKey() { return 0; }
 
   void Generate(MacroAssembler* masm);
 };
@@ skipping 360 matching lines @@
 
   class LookupModeBits: public BitField<LookupMode, 0, 1> {};
 
   LookupMode mode_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MIPS_CODE_STUBS_ARM_H_