Bug 1396230 - Clear PerformanceObserver mQueuedEntries right after they were copied to PerformanceObserverEntryList. r=baku

This matches to the spec and makes po-callback-mutate.any.js test pass.

From the spec [1]

  1. Let entries be a copy of po’s observer buffer.
  2. Empty po’s observer buffer.
  3. If entries is non-empty, call po’s callback with entries as first
     argument and po as the second argument and callback this value. If this
     throws an exception, report the exception.

[1] https://w3c.github.io/performance-timeline/#queue-a-performanceentry

MozReview-Commit-ID: AEdfvGpauzy

--HG--
extra : rebase_source : 20b9fc8426fd48d10e8e55662afe1c881fd92343

dom/performance/PerformanceObserver.cpp

@@ -113,12 +113,13 @@ PerformanceObserver::Notify()
   RefPtr<PerformanceObserverEntryList> list =
     new PerformanceObserverEntryList(this, mQueuedEntries);
 
+  mQueuedEntries.Clear();
+
   ErrorResult rv;
   mCallback->Call(this, *list, *this, rv);
   if (NS_WARN_IF(rv.Failed())) {
     rv.SuppressException();
   }
-  mQueuedEntries.Clear();
 }
 
 void

testing/web-platform/meta/performance-timeline/po-callback-mutate.any.js.ini

@@ -1,13 +0,0 @@
-[po-callback-mutate.any.worker.html]
-  type: testharness
-  expected: TIMEOUT
-  [PerformanceObserver modifications inside callback should update filtering and not clear buffer]
-    expected: TIMEOUT
-
-
-[po-callback-mutate.any.html]
-  type: testharness
-  expected: TIMEOUT
-  [PerformanceObserver modifications inside callback should update filtering and not clear buffer]
-    expected: TIMEOUT
-