Merge branch '24927-custom-event-polyfill-test' into 'master'

Adds tests for Custom Event polyfill

## What does this MR do?
Adds tests for CustomEvent polyfill.

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #24927

See merge request !7996

1 files changed, 4 insertions, 0 deletions

diff --git a/changelogs/unreleased/24927-custom-event-polyfill-test.yml b/changelogs/unreleased/24927-custom-event-polyfill-test.yml
new file mode 100644
index 00000000000..879c28a951e
--- /dev/null
+++ b/changelogs/unreleased/24927-custom-event-polyfill-test.yml
@@ -0,0 +1,4 @@
+---
+title: Adds tests for custom event polyfill
+merge_request: 7996
+author: