Test closure parameters without calling the parameter

This way, we can test if failure is occurring in the as a result
of binding arguments in the function that accepts a closure parameter,
rather than calling the closure parameter itself.  For example:

    my sub call-me(&blondie:(Str)) { blondie('') }

Does `call-me(-> Int $foo { })` fail while binding `call-me` or
`&blondie`?