Revert of Migrate Object.prototype.valueOf to CSA

src/builtins/builtins-object.cc

 // Copyright 2016 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.
 
 #include "src/builtins/builtins-object.h"
 #include "src/builtins/builtins-utils.h"
 #include "src/builtins/builtins.h"
 #include "src/code-factory.h"
 #include "src/code-stub-assembler.h"
 #include "src/counters.h"
@@ skipping 292 matching lines @@
       // Return object if the proxy {receiver} is not callable.
       Branch(IsCallableMap(map), &return_function, &return_object);
     }
 
     // Default
     Bind(&return_object);
     Return(HeapConstant(isolate()->factory()->object_to_string()));
   }
 }
 
-// ES6 19.3.7 Object.prototype.valueOf
-TF_BUILTIN(ObjectPrototypeValueOf, CodeStubAssembler) {
-  Node* receiver = Parameter(0);
-  Node* context = Parameter(3);
-
-  Callable to_object = CodeFactory::ToObject(isolate());
-  receiver = CallStub(to_object, context, receiver);
-
-  Return(receiver);
-}
-
 TF_BUILTIN(ObjectCreate, ObjectBuiltinsAssembler) {
   Node* prototype = Parameter(1);
   Node* properties = Parameter(2);
   Node* context = Parameter(3 + 2);
 
   Label call_runtime(this, Label::kDeferred), prototype_valid(this),
       no_properties(this);
   {
     Comment("Argument 1 check: prototype");
     GotoIf(WordEqual(prototype, NullConstant()), &prototype_valid);
@@ skipping 671 matching lines @@
   typedef TypeofDescriptor Descriptor;
 
   Node* object = Parameter(Descriptor::kObject);
   Node* context = Parameter(Descriptor::kContext);
 
   Return(GetSuperConstructor(object, context));
 }
 
 }  // namespace internal
 }  // namespace v8