Get rid of the unused native code StringAddStub.

src/ia32/lithium-codegen-ia32.cc

 // 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 4889 matching lines @@
   PushSafepointRegistersScope scope(this);
   __ SmiTag(char_code);
   __ push(char_code);
   CallRuntimeFromDeferred(Runtime::kCharFromCode, 1, instr, instr->context());
   __ StoreToSafepointRegisterSlot(result, eax);
 }
 
 
 void LCodeGen::DoStringAdd(LStringAdd* instr) {
   ASSERT(ToRegister(instr->context()).is(esi));
-  if (FLAG_new_string_add) {
-    ASSERT(ToRegister(instr->left()).is(edx));
-    ASSERT(ToRegister(instr->right()).is(eax));
-    NewStringAddStub stub(instr->hydrogen()->flags(),
-                          instr->hydrogen()->pretenure_flag());
-    CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
-  } else {
-    EmitPushTaggedOperand(instr->left());
-    EmitPushTaggedOperand(instr->right());
-    StringAddStub stub(instr->hydrogen()->flags());
-    CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
-  }
+  ASSERT(ToRegister(instr->left()).is(edx));
+  ASSERT(ToRegister(instr->right()).is(eax));
+  StringAddStub stub(instr->hydrogen()->flags(),
+                     instr->hydrogen()->pretenure_flag());
+  CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
 }
 
 
 void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
   LOperand* input = instr->value();
   LOperand* output = instr->result();
   ASSERT(input->IsRegister() || input->IsStackSlot());
   ASSERT(output->IsDoubleRegister());
   if (CpuFeatures::IsSupported(SSE2)) {
     CpuFeatureScope scope(masm(), SSE2);
@@ skipping 1430 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32