If a function seems small, worker/wrapper won't split it; instead
it turns it into an INLINE function.

But if it's a /bottoming/ function that's a bad idea.  We want
don't want to inline bottoming functions unless they are /really/
small (smaller than the call itself) and that's handled by a
different branch in certainlyWillInline.

So this patch adds a not-bottom test to the UnfIfGoodArgs case of
certainlyWillInline.

No big perf effect, but this will tend to keep error code out of
functions, and hence make them a bit more likely to inline.

I fell over this when fiddling with #13144