[cleanup] TNodify last VARIABLE in generator-gen.cc

Bug: v8:9810
Change-Id: Ie371220afd332322cc3d613f7c84ca254bd5dd78
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1895556
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64729}

src/builtins/builtins-generator-gen.cc

@@ -56,7 +56,7 @@ void GeneratorBuiltinsAssembler::InnerResume(
                                  SmiConstant(resume_mode));
 
   // Resume the {receiver} using our trampoline.
-  VARIABLE(var_exception, MachineRepresentation::kTagged, UndefinedConstant());
+  TVARIABLE(HeapObject, var_exception);
   Label if_exception(this, Label::kDeferred), if_final_return(this);
   TNode<Object> result = CallStub(CodeFactory::ResumeGenerator(isolate()),
                                   context, value, receiver);