Auto merge of #12501 - mephisto41:worker-close-impl, r=KiChjang

Implement DedicatedWorkerGlobalScope.close

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Implement DedicatedWorkerGlobalScope.close().
---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12466 (github issue number if applicable).

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- [X] There are tests for these changes

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components/script/dom/workerglobalscope.rs

@@ -444,4 +444,10 @@ impl WorkerGlobalScope {
     pub fn set_devtools_wants_updates(&self, value: bool) {
         self.devtools_wants_updates.set(value);
     }
+
+    pub fn close(&self) {
+        if let Some(ref closing) = self.closing {
+            closing.store(true, Ordering::SeqCst);
+        }
+    }
 }