no implicit any when indexing never

[sandersn]

// @noImplicitAny: true
function f(l: never, x: any) {
  var x = l[0] // should be implicit any error here, but 'non-matching redeclaration type' instead
  x.length  // and no error here, but 'length' not found on 'never' instead
}

Expected behavior:
With noImplicitAny on, you should get a noImplicitAny error and x: any. With it off, you should just get x: any.

Actual behavior:
x: never and you get an error on the next line that 'length' does not exist on type 'never'.

On master, but not 3.1 as of 2018/07/17

[ahejlsberg]

This is an intended effect of #26340. We definitely want T[K] to be never when T is never.