A key parameter took no fallback arm when every call edge of its
function passed a string literal key of the table. A call through
`call` or `apply` passes the this value first, so `f.call("a", "c")`
looked like a call with the key "a", and the dispatch for "c" called
the table's last member where Node throws a TypeError. A builtin that
calls the function back chooses its own arguments too.
Each call now has to name the function itself: its callee is a binding,
or a constant object's member, whose values are only that function.
Chris Tate
97787329c2