a worker/wrapper, in which the worker has turned into a single variable:
$wf = h
f = \x -> ...$wf...
-Now CSE may transoform to
+Now CSE may transform to
f = \x -> ...h...
But the WorkerInfo for f still says $wf, which is now dead! This won't
happen now that we don't look inside INLINEs (which wrappers are).