diff --git a/testing/web-platform/tests/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js b/testing/web-platform/tests/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
index 5f8e07711cbca..95d516e275280 100644
--- a/testing/web-platform/tests/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
+++ b/testing/web-platform/tests/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
@@ -46,40 +46,3 @@ async function assertHeaderIsAsExpected(
         return res.headers.get(headerName);
       }, [headerName]), 'header is set');
 }
-
-async function  assertNotRestoredReasonsEquals(
-  remoteContextHelper, blocked, url, src, id, name, reasons, children) {
-  let result = await remoteContextHelper.executeScript(() => {
-    return performance.getEntriesByType('navigation')[0].notRestoredReasons;
-  });
-  assertReasonsStructEquals(result, blocked, url, src, id, name, reasons, children);
-}
-
-function assertReasonsStructEquals(result, blocked, url, src, id, name, reasons, children) {
-  assert_equals(result.blocked, blocked);
-  assert_equals(result.url, url);
-  assert_equals(result.src, src);
-  assert_equals(result.id, id);
-  assert_equals(result.name, name);
-  // Reasons should match.
-  assert_equals(result.reasons.length, reasons.length);
-  reasons.sort();
-  result.reasons.sort();
-  for (let i=0; i<reasons.length; i++) {
-    assert_equals(result.reasons[i], reasons[i]);
-  }
-  // Children should match.
-  assert_equals(result.children.length, children.length);
-  children.sort();
-  result.children.sort();
-  for (let j=0; j<children.length; j++) {
-    assertReasonsStructEquals(result.children[0],
-      children[0].blocked,
-      children[0].url,
-      children[0].src,
-      children[0].id,
-      children[0].name,
-      children[0].reasons,
-      children[0].children);
-  }
-}
\ No newline at end of file
diff --git a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-bfcache.window.js b/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-bfcache.window.js
deleted file mode 100644
index 549e72b30dd63..0000000000000
--- a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-bfcache.window.js
+++ /dev/null
@@ -1,31 +0,0 @@
-// META: title=RemoteContextHelper navigation using BFCache
-// META: script=/common/dispatcher/dispatcher.js
-// META: script=/common/get-host-info.sub.js
-// META: script=/common/utils.js
-// META: script=/resources/testharness.js
-// META: script=/resources/testharnessreport.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
-
-'use strict';
-
-// Ensure that notRestoredReasons is empty for successful BFCache restore.
-promise_test(async t => {
-  const rcHelper = new RemoteContextHelper();
-
-  // Open a window with noopener so that BFCache will work.
-  const rc1 = await rcHelper.addWindow(
-      /*config=*/ null, /*options=*/ {features: 'noopener'});
-
-  // Navigate away.
-  const rc2 = await rc1.navigateToNew();
-
-  // Navigate back.
-  await rc2.historyBack();
-
-  // Verify that no reasons are recorded for successful restore.
-  assert_true(await rc1.executeScript(() => {
-    let reasons = performance.getEntriesByType('navigation')[0].notRestoredReasons;
-    return reasons == null;
-  }));
-});
\ No newline at end of file
diff --git a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-cross-origin-bfcache.window.js b/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-cross-origin-bfcache.window.js
deleted file mode 100644
index f906b4b0735af..0000000000000
--- a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-cross-origin-bfcache.window.js
+++ /dev/null
@@ -1,70 +0,0 @@
-// META: title=RemoteContextHelper navigation using BFCache
-// META: script=/common/dispatcher/dispatcher.js
-// META: script=/common/get-host-info.sub.js
-// META: script=/common/utils.js
-// META: script=/resources/testharness.js
-// META: script=/resources/testharnessreport.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
-// META: script=/websockets/constants.sub.js
-
-'use strict';
-
-// Ensure that cross-origin subtree's reasons are not exposed to notRestoredReasons.
-promise_test(async t => {
-  const rcHelper = new RemoteContextHelper();
-  // Open a window with noopener so that BFCache will work.
-  const rc1 = await rcHelper.addWindow(
-      /*config=*/ null, /*options=*/ {features: 'noopener'});
-  const rc1_url = await rc1.executeScript(() => {
-    return location.href;
-  });
-  // Add a cross-origin iframe and use BroadcastChannel.
-  const rc1_child = await rc1.addIframe(
-    /*extraConfig=*/ {
-      origin: 'HTTP_REMOTE_ORIGIN',
-      scripts: [],
-      headers: [],
-    },
-    /*attributes=*/ {id: 'test-id'},
-  );
-
-  const domainPort = SCHEME_DOMAIN_PORT;
-  await rc1_child.executeScript((domain) => {
-    var ws = new WebSocket(domain + '/echo');
-  }, [domainPort]);
-
-  const rc1_child_url = await rc1_child.executeScript(() => {
-    return location.href;
-  });
-  // Add a child to the iframe.
-  const rc1_grand_child = await rc1_child.addIframe();
-  const rc1_grand_child_url = await rc1_grand_child.executeScript(() => {
-    return location.href;
-  });
-
-  // Navigate away.
-  const rc2 = await rc1.navigateToNew();
-
-  // Navigate back.
-  await rc2.historyBack();
-
-  // Check the reported reasons.
-  await assertNotRestoredReasonsEquals(
-    rc1,
-    /*blocked=*/false,
-    /*url=*/rc1_url,
-    /*src=*/ "",
-    /*id=*/"",
-    /*name=*/"",
-    /*reasons=*/[],
-    /*children=*/[{
-      "blocked": true,
-      "url": "",
-      "src": "",
-      "id": "",
-      "name": "",
-      "reasons": [],
-      "children": []
-    }]);
-});
\ No newline at end of file
diff --git a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-not-bfcached.window.js b/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-not-bfcached.window.js
deleted file mode 100644
index ac8af0e88c8a4..0000000000000
--- a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-not-bfcached.window.js
+++ /dev/null
@@ -1,44 +0,0 @@
-// META: title=RemoteContextHelper navigation using BFCache
-// META: script=/common/dispatcher/dispatcher.js
-// META: script=/common/get-host-info.sub.js
-// META: script=/common/utils.js
-// META: script=/resources/testharness.js
-// META: script=/resources/testharnessreport.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
-// META: script=/websockets/constants.sub.js
-
-'use strict';
-
-// Ensure that notRestoredReasons is populated when not restored.
-promise_test(async t => {
-  const rcHelper = new RemoteContextHelper();
-  // Open a window with noopener so that BFCache will work.
-  const rc1 = await rcHelper.addWindow(
-      /*config=*/ null, /*options=*/ {features: 'noopener'});
-
-  const domainPort = SCHEME_DOMAIN_PORT;
-  await rc1.executeScript((domain) => {
-    var ws = new WebSocket(domain + '/echo');
-  }, [domainPort]);
-
-  const rc1_url = await rc1.executeScript(() => {
-    return location.href;
-  });
-
-  // Navigate away.
-  const rc2 = await rc1.navigateToNew();
-
-  // Navigate back.
-  await rc2.historyBack();
-  // Check the reported reasons.
-  await assertNotRestoredReasonsEquals(
-    rc1,
-    /*blocked=*/true,
-    /*url=*/rc1_url,
-    /*src=*/ "",
-    /*id=*/"",
-    /*name=*/"",
-    /*reasons=*/["WebSocket"],
-    /*children=*/[]);
-});
\ No newline at end of file
diff --git a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-same-origin-bfcache.window.js b/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-same-origin-bfcache.window.js
deleted file mode 100644
index fb5ec50400e5a..0000000000000
--- a/testing/web-platform/tests/performance-timeline/not-restored-reasons/performance-navigation-timing-same-origin-bfcache.window.js
+++ /dev/null
@@ -1,73 +0,0 @@
-// META: title=RemoteContextHelper navigation using BFCache
-// META: script=/common/dispatcher/dispatcher.js
-// META: script=/common/get-host-info.sub.js
-// META: script=/common/utils.js
-// META: script=/resources/testharness.js
-// META: script=/resources/testharnessreport.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
-// META: script=/html/browsers/browsing-the-web/remote-context-helper-tests/resources/test-helper.js
-// META: script=/websockets/constants.sub.js
-
-'use strict';
-
-// Ensure that same-origin subtree's reasons are exposed to notRestoredReasons.
-promise_test(async t => {
-  const rcHelper = new RemoteContextHelper();
-  // Open a window with noopener so that BFCache will work.
-  const rc1 = await rcHelper.addWindow(
-      /*config=*/ null, /*options=*/ {features: 'noopener'});
-  const rc1_url = await rc1.executeScript(() => {
-    return location.href;
-  });
-  // Add a same-origin iframe and use WebSocket.
-  const rc1_child = await rc1.addIframe(/*extra_config=*/{}, /*attributes=*/ {id: 'test-id'});
-
-  const domainPort = SCHEME_DOMAIN_PORT;
-  await rc1_child.executeScript((domain) => {
-    var ws = new WebSocket(domain + '/echo');
-  }, [domainPort]);
-
-  const rc1_child_url = await rc1_child.executeScript(() => {
-    return location.href;
-  });
-  // Add a child to the iframe.
-  const rc1_grand_child = await rc1_child.addIframe();
-  const rc1_grand_child_url = await rc1_grand_child.executeScript(() => {
-    return location.href;
-  });
-
-  // Navigate away.
-  const rc2 = await rc1.navigateToNew();
-
-  // Navigate back.
-  await rc2.historyBack();
-
-  // Check the reported reasons.
-  await assertNotRestoredReasonsEquals(
-    rc1,
-    /*blocked=*/false,
-    /*url=*/rc1_url,
-    /*src=*/ "",
-    /*id=*/"",
-    /*name=*/"",
-    /*reasons=*/[],
-    /*children=*/[{
-      "blocked": true,
-      "url": rc1_child_url,
-      "src": rc1_child_url,
-      "id": "test-id",
-      "name": "",
-      "reasons": ["WebSocket"],
-      "children": [
-        {
-        "blocked": false,
-        "url": rc1_grand_child_url,
-        "src": rc1_grand_child_url,
-        "id": "",
-        "name": "",
-        "reasons": [],
-        "children": []
-        }
-      ]
-    }]);
-});
\ No newline at end of file