Calendar: import el-button and el-button-group (#17376)

packages/calendar/src/main.vue

@@ -59,6 +59,8 @@
 <script>
 import Locale from 'element-ui/src/mixins/locale';
 import fecha from 'element-ui/src/utils/date';
+import ElButton from 'element-ui/packages/button';
+import ElButtonGroup from 'element-ui/packages/button-group';
 import DateTable from './date-table';
 import { validateRangeInOneMonth } from 'element-ui/src/utils/date-util';
 
@@ -72,7 +74,9 @@ export default {
   mixins: [Locale],
 
   components: {
-    DateTable
+    DateTable,
+    ElButton,
+    ElButtonGroup
   },
 
   props: {

packages/theme-chalk/src/calendar.scss

 @import "mixins/mixins";
 @import "common/var";
+@import "button";
+@import "button-group";
 
 @include b(calendar) {
   background-color:#fff;