Bug 1671358 [wpt PR 26119] - Revert "[Longtasks] Fix buffering before observer", a=testonly

Automatic update from web-platform-tests
Revert "[Longtasks] Fix buffering before observer"

This reverts commit c2d62d3604e218cfd1b62877684c634980aea3f7.

Reason for revert: suspect for crbug.com/1138522

Original change's description:
> [Longtasks] Fix buffering before observer
>
> When we shipped longtasks with buffered flag, we forgot to remove a
> check that would prevent longtask creation when there's no observer.
> This CL fixes this and adds a test for this case. It also moves the
> UseCounter to the observe() method.
>
> Bug: 1131385
> Change-Id: I2911b9ab044db7394bcf64f64b1e599959cbdc37
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463594
> Reviewed-by: Steve Kobes <skobes@chromium.org>
> Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#816664}

TBR=skobes@chromium.org,npm@chromium.org

Change-Id: I03483b9cc1e8ce03b518d90df16e54e4503f5ffc
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1131385
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2472258
Reviewed-by: Kramer Ge <fangzhoug@chromium.org>
Commit-Queue: Kramer Ge <fangzhoug@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817101}

--

wpt-commits: 399db71122d26363cf3c5e41bb97b4ff06caf85c
wpt-pr: 26119

testing/web-platform/tests/longtask-timing/longtask-before-observer.window.js

@@ -1,16 +0,0 @@
-async_test(t => {
-  assert_implements(window.PerformanceLongTaskTiming, 'Longtasks are not supported.');
-  // Create a long task before any observer.
-  const begin = window.performance.now();
-  while (window.performance.now() < begin + 60);
-  // After a timeout, add an observer with buffered flag.
-  t.step_timeout(() => {
-    new PerformanceObserver(t.step_func_done(list => {
-      list.getEntries().forEach(entry => {
-        assert_equals(entry.entryType, 'longtask');
-        assert_equals(entry.name, 'self');
-        assert_greater_than(entry.duration, 50);
-      });
-    })).observe({type: 'longtask', buffered: true});
-  }, 0);
-}, 'PerformanceObserver with buffered flag can see previous longtask entries.');