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>

Author: justinbhopper

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
       }