[builtins] Fix type of exception variable

Exception variables can be Object (e.g. throw 4) so loosen the type from
HeapObject.

Bug: v8:9810
Change-Id: I14600978ed5159b2b661bd09e69ad6d6530553ed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1906566
Commit-Queue: Dan Elphick <delphick@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64861}

src/builtins/builtins-generator-gen.cc

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