Fix exception on older browsers

Closes GH-246.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Remco Haszing <remcohaszing@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

lib/callable-instance.js

@@ -26,12 +26,17 @@ export const CallableInstance =
 
  Object.setPrototypeOf(apply, proto)
 
- const names = Object.getOwnPropertyNames(value)
-
- for (const p of names) {
- const descriptor = Object.getOwnPropertyDescriptor(value, p)
- if (descriptor) Object.defineProperty(apply, p, descriptor)
- }
+ // Not needed for us in `unified`: we only call this on the `copy`
+ // function,
+ // and we don't need to add its fields (`length`, `name`)
+ // over.
+ // See also: GH-246.
+ // const names = Object.getOwnPropertyNames(value)
+ //
+ // for (const p of names) {
+ // const descriptor = Object.getOwnPropertyDescriptor(value, p)
+ // if (descriptor) Object.defineProperty(apply, p, descriptor)
+ // }
 
  return apply
  }