[array.unique]: use Set to create unique item array

src/array/unique.js

@@ -1,10 +1,8 @@
 import checkArray from "./_checkArray";
+import Set from 'core-js/es6/set';
 
 /**
  * @memberOf array
  * @param ar
  */
-export default (ar) => {
-    checkArray(ar);
-    return ar.filter((val, i, input) => i === input.indexOf(val));
-}
+export default (ar) => [...new Set(ar)];