Auto merge of #18176 - rtbo:perf_observer_buffered, r=ferjm

PerformanceObserverInit.buffered

Per #18108, add `buffered` flag in the `PerformanceObserverInit` dict.
Per W3C spec, when `buffered` is set, `PerformanceObserver.observe()` method adds the entries buffered in the `Performance` instance into the observer's entry buffer.
One step is the implementation of the [filter by name and type](https://w3c.github.io/performance-timeline/#filter-buffer-by-name-and-type) algorithm. Don't think that the sort operation is useful in this case, but the spec states that this algorithm is to be used.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #18108
- [X] These changes do not require tests (yet) because the timeline API is not powered.

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components/script/dom/performanceobserver.rs

@@ -89,23 +89,30 @@ impl PerformanceObserver {
     pub fn entries(&self) -> DOMPerformanceEntryList {
         self.entries.borrow().clone()
     }
+
+    pub fn set_entries(&self, entries: DOMPerformanceEntryList) {
+        *self.entries.borrow_mut() = entries;
+    }
 }
 
 impl PerformanceObserverMethods for PerformanceObserver {
     // https://w3c.github.io/performance-timeline/#dom-performanceobserver-observe()
     fn Observe(&self, options: &PerformanceObserverInit) -> Fallible<()> {
+        // step 1
         // Make sure the client is asking to observe events from allowed entry types.
         let entry_types = options.entryTypes.iter()
                                             .filter(|e| VALID_ENTRY_TYPES.contains(&e.as_ref()))
                                             .map(|e| e.clone())
                                             .collect::<Vec<DOMString>>();
+        // step 2
         // There must be at least one valid entry type.
         if entry_types.is_empty() {
             return Err((Error::Type("entryTypes cannot be empty".to_string())));
         }
 
         let performance = self.global().as_window().Performance();
-        performance.add_observer(self, entry_types);
+        // step 3-4-5
+        performance.add_observer(self, entry_types, options.buffered);
         Ok(())
     }