Auto merge of #12342 - ChangWanHong:trivial, r=KiChjang

Add name method for Runnable trait into DetailsNotificationRunnable

<!-- Please describe your changes on the following line: -->

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12332 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because it's sorta trivial as stated in issue description.

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/12342)
<!-- Reviewable:end -->

components/script/dom/htmldetailselement.rs

@@ -90,6 +90,8 @@ pub struct DetailsNotificationRunnable {
 }
 
 impl Runnable for DetailsNotificationRunnable {
+    fn name(&self) -> &'static str { "DetailsNotificationRunnable" }
+
     fn handler(self: Box<DetailsNotificationRunnable>) {
         let target = self.element.root();
         if target.check_toggle_count(self.toggle_number) {