Auto merge of #18372 - tigercosmos:userTimingApi, r=ferjm

TEST: fix and add case of po-observe.any.js

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1. implementing step 3 from the [`PerformanceObserver.observe()`](https://w3c.github.io/performance-timeline/#dom-performanceobserver-observe()) method spec properly.
2. also add cases about step 1 & 2

work on the top of #18283

 r? @ferjm
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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 #18285 (github issue number if applicable).

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- [ ] There are tests for these changes OR
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components/script/dom/performance.rs

@@ -163,7 +163,7 @@ impl Performance {
             observer.set_entries(obs_entries);
         }
         let mut observers = self.observers.borrow_mut();
-        match observers.iter().position(|o| &(*o.observer) == observer) {
+        match observers.iter().position(|o| *o.observer == *observer) {
             // If the observer is already in the list, we only update the observed
             // entry types.
             Some(p) => observers[p].entry_types = entry_types,