Handle argument conversion in StringAddStub.

src/ia32/codegen-ia32.cc

 // Copyright 2010 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 1393 matching lines @@
            right_is_string);
     if (left_is_string || right_is_string) {
       frame_->Push(&left);
       frame_->Push(&right);
       Result answer;
       if (left_is_string) {
         if (right_is_string) {
           StringAddStub stub(NO_STRING_CHECK_IN_STUB);
           answer = frame_->CallStub(&stub, 2);
         } else {
-          answer =
-            frame_->InvokeBuiltin(Builtins::STRING_ADD_LEFT, CALL_FUNCTION, 2);
+          StringAddStub stub(NO_STRING_CHECK_LEFT_IN_STUB);
+          answer = frame_->CallStub(&stub, 2);
         }
       } else if (right_is_string) {
-        answer =
-          frame_->InvokeBuiltin(Builtins::STRING_ADD_RIGHT, CALL_FUNCTION, 2);
+        StringAddStub stub(NO_STRING_CHECK_RIGHT_IN_STUB);
+        answer = frame_->CallStub(&stub, 2);
       }
       answer.set_type_info(TypeInfo::String());
       frame_->Push(&answer);
       return;
     }
     // Neither operand is known to be a string.
   }
 
   bool left_is_smi_constant = left.is_constant() && left.handle()->IsSmi();
   bool left_is_non_smi_constant = left.is_constant() && !left.handle()->IsSmi();
@@ skipping 8603 matching lines @@
   masm.GetCode(&desc);
   // Call the function from C++.
   return FUNCTION_CAST<MemCopyFunction>(buffer);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32