contextually typing IIFE parameters doesn't work with tuple spread in arguments

[ajafff]

TypeScript Version: 3.0.0-dev.20160628

Search Terms:

Code

declare var tuple: [number, string];
(function foo(a, b){}(...tuple));

Expected behavior:

No error.
a is inferred as number
b is inferred as string

Actual behavior:

a is inferred as string | number
b is inferred as undefined
Error Argument of type 'string' is not assignable to parameter of type 'undefined'.

Playground Link:

Related: #24897