The keyword tries to remove a method of the same name which is unlikely
to be the intention of this test:
$ ruby -e 'undef Object'
-e:1:in '<main>': undefined method 'Object' for class 'Object' (NameError)
Found looking at GH-11497. The NameError triggers error_highlight, which
loads a bunch of file under GC.stress set by this test when using Prism.
That takes a long time, causing a timeout.