[builtins] Fix pointer comparison in ToString builtin.

src/builtins/builtins-object.cc

Index: src/builtins/builtins-object.cc
diff --git a/src/builtins/builtins-object.cc b/src/builtins/builtins-object.cc
index 01f5ad45863df21f67a1fbae052206e74cc150db..c037e11d4f4c7cb54eca74b714d2c19e99986408 100644
--- a/src/builtins/builtins-object.cc
+++ b/src/builtins/builtins-object.cc
@@ -296,10 +296,10 @@ void Builtins::Generate_ObjectProtoToString(CodeStubAssembler* assembler) {
   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);