Remove duplicate C++ implementation of Object.prototype.toString

src/objects.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 1478 matching lines @@
   bool IterationHasObservableEffects();
 
   DECLARE_VERIFIER(Object)
 #ifdef VERIFY_HEAP
   // Verify a pointer is a valid object pointer.
   static void VerifyPointer(Object* p);
 #endif
 
   inline void VerifyApiCallResultType();
 
-  // ES6 19.1.3.6 Object.prototype.toString
-  MUST_USE_RESULT static MaybeHandle<String> ObjectProtoToString(
-      Isolate* isolate, Handle<Object> object);
-
   // Prints this object without details.
   void ShortPrint(FILE* out = stdout);
 
   // Prints this object without details to a message accumulator.
   void ShortPrint(StringStream* accumulator);
 
   void ShortPrint(std::ostream& os);  // NOLINT
 
   DECLARE_CAST(Object)
 
@@ skipping 10195 matching lines @@
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #include "src/objects/object-macros-undef.h"
 
 #endif  // V8_OBJECTS_H_