[builtins] Fix pointer comparison in ToString builtin.

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.h"
 #include "src/builtins/builtins-utils.h"
 
 #include "src/code-factory.h"
 #include "src/property-descriptor.h"
 
@@ skipping 278 matching lines @@
 
   Label if_isproxy(assembler, Label::kDeferred);
 
   Label checkstringtag(assembler);
   Label if_tostringtag(assembler), if_notostringtag(assembler);
 
   Node* receiver = assembler->Parameter(0);
   Node* context = assembler->Parameter(3);
 
   assembler->GotoIf(
-      assembler->Word32Equal(receiver, assembler->UndefinedConstant()),
+      assembler->WordEqual(receiver, assembler->UndefinedConstant()),
       &return_undefined);
 
-  assembler->GotoIf(assembler->Word32Equal(receiver, assembler->NullConstant()),
+  assembler->GotoIf(assembler->WordEqual(receiver, assembler->NullConstant()),
                     &return_null);
 
   assembler->GotoIf(assembler->TaggedIsSmi(receiver), &return_number);
 
   Node* receiver_instance_type = assembler->LoadInstanceType(receiver);
   ReturnIfPrimitive(assembler, receiver_instance_type, &return_string,
                     &return_boolean, &return_number);
 
   // for proxies, check IsArray before getting @@toStringTag
   Variable var_proxy_is_array(assembler, MachineRepresentation::kTagged);
@@ skipping 733 matching lines @@
   typedef CompareDescriptor Descriptor;
   Node* object = assembler->Parameter(Descriptor::kLeft);
   Node* callable = assembler->Parameter(Descriptor::kRight);
   Node* context = assembler->Parameter(Descriptor::kContext);
 
   assembler->Return(assembler->InstanceOf(object, callable, context));
 }
 
 }  // namespace internal
 }  // namespace v8