[builtins] Tnodify builtins-microtask-queue-gen.cc

Converts last remaining Node*.

Bug: v8:6949
Change-Id: I792a7efa3dc3cdfd0e0ae8349aad6da54f4e8db8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1871928
Auto-Submit: Dan Elphick <delphick@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64431}

src/builtins/builtins-microtask-queue-gen.cc

@@ -147,7 +147,7 @@ void MicrotaskQueueBuiltinsAssembler::RunSingleMicrotask(
 
     TNode<JSReceiver> callable =
         LoadObjectField<JSReceiver>(microtask, CallableTask::kCallableOffset);
-    Node* const result = CallJS(
+    const TNode<Object> result = CallJS(
         CodeFactory::Call(isolate(), ConvertReceiverMode::kNullOrUndefined),
         microtask_context, callable, UndefinedConstant());
     GotoIfException(result, &if_exception, &var_exception);