Merge pull request #1004 from Jack-Works/groupByMap

Author: zloirock

README.md

@@ -2399,6 +2399,7 @@ Modules [`esnext.array.group-by`](https://github.com/zloirock/core-js/blob/maste
 ```js
 class Array {
   groupBy(callbackfn: (value: any, index: number, target: any) => key, thisArg?: any): { [key]: Array<mixed> };
+  groupByMap(callbackfn: (value: any, index: number, target: any) => key, thisArg?: any): Map<key, Array<mixed>>;
 }
 
 class %TypedArray% {

tests/compat/tests.js

@@ -1221,6 +1221,9 @@ GLOBAL.tests = {
   'esnext.array.group-by': function () {
     return [].groupBy;
   },
+  'esnext.array.group-by-map': function () {
+    return [].groupByMap;
+  },
   'esnext.array.is-template-object': function () {
     return Array.isTemplateObject;
   },