Revert "[WPT] BFCache: service worker clients"

This reverts commit 756b8281b5b76b2ae4561d3cf8c29a46689cf23f.

Reason for revert: New tests are very flaky. Example:
https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVylgELEgVGbGFrZSKKAWNocm9taXVtQGJsaW5rX3dlYl90ZXN0c0BleHRlcm5hbC93cHQvaHRtbC9icm93c2Vycy9icm93c2luZy10aGUtd2ViL2JhY2stZm9yd2FyZC1jYWNoZS9zZXJ2aWNlLXdvcmtlci1jb250cm9sbGVkLWFmdGVyLXJlc3RvcmUuaHR0cHMuaHRtbAw

https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyjgELEgVGbGFrZSKCAWNocm9taXVtQGJsaW5rX3dlYl90ZXN0c0BleHRlcm5hbC93cHQvaHRtbC9icm93c2Vycy9icm93c2luZy10aGUtd2ViL2JhY2stZm9yd2FyZC1jYWNoZS9zZXJ2aWNlLXdvcmtlci1jbGllbnRzLW1hdGNoYWxsLmh0dHBzLmh0bWwM

Original change's description:
> [WPT] BFCache: service worker clients
>
> This CL adds service worker tests for BFCache:
>
> - navigator.serviceWorker.controller
> - Fetch interception
> - Clients.claim()
> - Clients.matchAll() and
> - unregister().
>
> Expected behavior:
>
> - Controlled pages should remain controlled after
>   restored from BFCache, i.e.
>   navigator.serviceWorker.controller should remain non-null
>   and fetch should be intercepted.
> - Clients.claim() should evict pages
>   that would be affected from BFCache.
> - Clients.matchAll() shouldn't list pages in BFCache.
> - unregister() should evict controlled pages from BFCache.
>
> Failing tests:
>
> - service-worker-clients-claim.https.html:
>   On Safari/Firefox, Clients.claim() doesn't evict pages from BFCache.
> - service-worker-controlled-after-restore.https.html:
>   On Firefox, fetches are not intercepted after restored from
>   BFCache while `navigator.serviceWorker.controller` is non-null.
> - service-worker-unregister.https.html:
>   Controlled pages aren't evicted by unregister() (all browsers).
>
> Bug: 1107415, 1204228, w3c/ServiceWorker#1594
> Change-Id: I73233cf917e31dd91b974823d5490d0190f0eade
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3201011
> Reviewed-by: Rakina Zata Amni <[email protected]>
> Reviewed-by: Ben Kelly <[email protected]>
> Commit-Queue: Hiroshige Hayashizaki <[email protected]>
> Cr-Commit-Position: refs/heads/main@{#1008327}

Bug: 1107415, 1204228, w3c/ServiceWorker#1594
Change-Id: I56ac20a492e2b1716d27867dc9c113b097833a6c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3708190
Bot-Commit: Rubber Stamper <[email protected]>
Owners-Override: Phillis Tang <[email protected]>
Auto-Submit: Phillis Tang <[email protected]>
Commit-Queue: Phillis Tang <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1014735}

html/browsers/browsing-the-web/back-forward-cache/resources/helper.sub.js

@@ -187,16 +187,3 @@ function runBfcacheTest(params, description) {
     }
   }, description);
 }
-
-// Call clients.claim() on the service worker
-async function claim(t, worker) {
-  const channel = new MessageChannel();
-  const saw_message = new Promise(function(resolve) {
-    channel.port1.onmessage = t.step_func(function(e) {
-      assert_equals(e.data, 'PASS', 'Worker call to claim() should fulfill.');
-      resolve();
-    });
-  });
-  worker.postMessage({port: channel.port2}, [channel.port2]);
-  await saw_message;
-}