Merge branch 'nfriend-add-promise-finally-polyfill' into 'master'

Add core-js polyfill for Promise.finally()

See merge request gitlab-org/gitlab-ce!25925

app/assets/javascripts/commons/polyfills.js

@@ -7,6 +7,7 @@ import 'core-js/fn/array/includes';
 import 'core-js/fn/object/assign';
 import 'core-js/fn/object/values';
 import 'core-js/fn/promise';
+import 'core-js/fn/promise/finally';
 import 'core-js/fn/string/code-point-at';
 import 'core-js/fn/string/from-code-point';
 import 'core-js/fn/string/includes';