[stubs] replaced ToString MacroAssembler Stub with CodeStubAssembler builtin

src/builtins/builtins.h

Index: src/builtins/builtins.h
diff --git a/src/builtins/builtins.h b/src/builtins/builtins.h
index 1e54f6e370d898f819cc13ce922ad64ab6699340..b7929e4a4c0d31adc2f932ccd1b0d43560b2501f 100644
--- a/src/builtins/builtins.h
+++ b/src/builtins/builtins.h
@@ -163,6 +163,7 @@ namespace internal {
   TFS(ToName, BUILTIN, kNoExtraICState, TypeConversion)                       \
   TFS(NonNumberToNumber, BUILTIN, kNoExtraICState, TypeConversion)            \
   TFS(ToNumber, BUILTIN, kNoExtraICState, TypeConversion)                     \
+  TFS(ToString, BUILTIN, kNoExtraICState, TypeConversion)                     \
                                                                               \
   /* Handlers */                                                              \
   ASH(KeyedLoadIC_Megamorphic, KEYED_LOAD_IC, kNoExtraICState)                \