Merge branch 'winh-destroy-mr-widget-polling' into 'master'

Cleanup polling of merge request widget in tests

Closes gitlab-ee#7728

See merge request gitlab-org/gitlab-ce!21906

app/assets/javascripts/vue_merge_request_widget/mr_widget_options.vue

@@ -114,6 +114,8 @@ export default {
   },
   beforeDestroy() {
     eventHub.$off('mr.discussion.updated', this.checkStatus);
+    this.pollingInterval.destroy();
+    this.deploymentsInterval.destroy();
   },
   methods: {
     createService(store) {

spec/javascripts/vue_mr_widget/mr_widget_options_spec.js

@@ -27,6 +27,10 @@ describe('mrWidgetOptions', () => {
     });
   });
 
+  afterEach(() => {
+    vm.$destroy();
+  });
+
   describe('data', () => {
     it('should instantiate Store and Service', () => {
       expect(vm.mr).toBeDefined();