From 8dd16259287f58f9273002717ec4d27e97127719 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 12 Jun 2024 07:43:14 +0200
Subject: Merging upstream version 127.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../media-elements/WEB_FEATURES.yml                |  4 +
 .../the-object-element/WEB_FEATURES.yml            |  4 +
 .../WEB_FEATURES.yml                               |  4 +
 .../semantics/forms/constraints/WEB_FEATURES.yml   |  3 +
 ...-validation-validity-textarea-defaultValue.html | 98 ++++++++++++++++++++++
 .../forms/the-button-element/WEB_FEATURES.yml      | 10 +++
 .../forms/the-fieldset-element/WEB_FEATURES.yml    |  8 ++
 .../forms/the-form-element/WEB_FEATURES.yml        |  4 +
 .../forms/the-input-element/WEB_FEATURES.yml       | 11 +++
 .../forms/the-input-element/input-stepdown-02.html | 42 ++++++++++
 .../forms/the-output-element/WEB_FEATURES.yml      |  5 ++
 .../forms/the-select-element/WEB_FEATURES.yml      |  9 ++
 .../native-popup-with-datalist-ref.html            | 17 ++++
 .../native-popup-with-datalist.tentative.html      | 25 ++++++
 .../stylable-select/nested-options.tenative.html   | 46 ++++++++++
 .../select-reset-non-interoperable-styles.css      |  5 --
 .../resources/stylable-select-styles.css           | 49 ++++++++++-
 ...t-appearance-custom-button-no-datalist-ref.html | 14 ++++
 ...arance-custom-button-no-datalist.tentative.html |  3 +-
 ...t-appearance-no-button-custom-datalist-ref.html | 14 ----
 ...arance-no-button-custom-datalist.tentative.html |  3 +-
 ...elect-appearance-no-button-no-datalist-ref.html | 17 ++++
 ...appearance-no-button-no-datalist.tentative.html |  3 +-
 ...ct-appearance-writing-mode-vertical-lr-ref.html | 23 +++++
 ...earance-writing-mode-vertical-lr.tentative.html | 29 +++++++
 ...ct-appearance-writing-mode-vertical-rl-ref.html | 23 +++++
 ...earance-writing-mode-vertical-rl.tentative.html | 29 +++++++
 ...button-and-datalist-invalidation.tentative.html |  1 -
 ...select-child-button-and-datalist.tentative.html |  1 -
 ...select-datalist-popover-behavior.tentative.html | 75 +++++++++++++++++
 .../select-keyboard-behavior.tentative.html        | 14 ++++
 ...tion-arbitrary-content-displayed.tentative.html |  2 +
 .../forms/the-textarea-element/WEB_FEATURES.yml    |  6 ++
 .../the-details-element/WEB_FEATURES.yml           |  4 +
 ...resttarget-anchor-event-dispatch.tentative.html | 47 +++++++++++
 ...teresttarget-area-event-dispatch.tentative.html | 50 +++++++++++
 ...resttarget-button-event-dispatch.tentative.html | 31 -------
 ...eresttarget-svg-a-event-dispatch.tentative.html | 51 +++++++++++
 .../invoketarget-on-input-number.tentative.html    | 78 +++++++++++++++++
 .../bounded-css-properties-reference-expected.html | 35 --------
 ...bounded-css-properties-reference.tentative.html | 37 --------
 .../bounded-css-properties-reftest-ref.html        | 35 ++++++++
 .../bounded-css-properties-reftest.tentative.html  | 37 ++++++++
 .../bounded-sizes-reftest-ref.html                 | 56 +++++++++++++
 .../bounded-sizes-reftest.tentative.html           | 68 +++++++++++++++
 .../bounded-sizes.tentative.html                   | 75 +++++++++++++++++
 .../display-css-property-reference-expected.html   | 16 ----
 .../display-css-property-reference.tentative.html  | 22 -----
 .../display-css-property-reftest-ref.html          | 16 ++++
 .../display-css-property-reftest.tentative.html    | 22 +++++
 .../popover-anchor-change-display.tentative.html   |  1 +
 .../popover-anchor-display-none.tentative.html     |  1 +
 .../popovers/popover-anchor-display.tentative.html |  1 +
 .../popover-anchor-scroll-display.tentative.html   |  1 +
 ...over-anchor-transition.tentative.tentative.html |  1 +
 .../html/semantics/popovers/popover-focus-2.html   |  2 +-
 .../popover-hover-crash-hang.tentative.html        | 34 ++++++++
 .../popover-light-dismiss-scroll-within.html       | 52 ++++++++++++
 .../semantics/popovers/popover-light-dismiss.html  | 56 ++++---------
 .../module/dynamic-import/microtasks/basic.any.js  |  4 +-
 .../module/inline-async-inserted-execorder.html    | 70 ++++++++++++++++
 .../the-template-element/WEB_FEATURES.yml          |  3 +
 .../selectors/pseudo-classes/WEB_FEATURES.yml      | 11 +++
 63 files changed, 1304 insertions(+), 214 deletions(-)
 create mode 100644 testing/web-platform/tests/html/semantics/embedded-content/media-elements/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/embedded-content/the-object-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/attributes-common-to-form-controls/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/constraints/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/constraints/form-validation-validity-textarea-defaultValue.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-button-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-fieldset-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-form-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-input-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-input-element/input-stepdown-02.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-output-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/nested-options.tenative.html
 delete mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/select-reset-non-interoperable-styles.css
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist-ref.html
 delete mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-datalist-popover-behavior.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/forms/the-textarea-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/interactive-elements/the-details-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/invokers/interesttarget-anchor-event-dispatch.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/invokers/interesttarget-area-event-dispatch.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/invokers/interesttarget-svg-a-event-dispatch.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/invokers/invoketarget-on-input-number.tentative.html
 delete mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference-expected.html
 delete mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/bounded-sizes.tentative.html
 delete mode 100644 testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference-expected.html
 delete mode 100644 testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest-ref.html
 create mode 100644 testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/popovers/popover-hover-crash-hang.tentative.html
 create mode 100644 testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss-scroll-within.html
 create mode 100644 testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/inline-async-inserted-execorder.html
 create mode 100644 testing/web-platform/tests/html/semantics/scripting-1/the-template-element/WEB_FEATURES.yml
 create mode 100644 testing/web-platform/tests/html/semantics/selectors/pseudo-classes/WEB_FEATURES.yml

(limited to 'testing/web-platform/tests/html/semantics')

diff --git a/testing/web-platform/tests/html/semantics/embedded-content/media-elements/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/embedded-content/media-elements/WEB_FEATURES.yml
new file mode 100644
index 0000000000..5730fe4715
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/embedded-content/media-elements/WEB_FEATURES.yml
@@ -0,0 +1,4 @@
+features:
+- name: preserves-pitch
+  files:
+  - preserves-pitch.html
diff --git a/testing/web-platform/tests/html/semantics/embedded-content/the-object-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/embedded-content/the-object-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..d3411c2d8d
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/embedded-content/the-object-element/WEB_FEATURES.yml
@@ -0,0 +1,4 @@
+features:
+- name: constraint-validation
+  files:
+  - object-setcustomvalidity.html
diff --git a/testing/web-platform/tests/html/semantics/forms/attributes-common-to-form-controls/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/attributes-common-to-form-controls/WEB_FEATURES.yml
new file mode 100644
index 0000000000..457c904005
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/attributes-common-to-form-controls/WEB_FEATURES.yml
@@ -0,0 +1,4 @@
+features:
+- name: dirname
+  files:
+  - dirname-*
diff --git a/testing/web-platform/tests/html/semantics/forms/constraints/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/constraints/WEB_FEATURES.yml
new file mode 100644
index 0000000000..93b4c5745f
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/constraints/WEB_FEATURES.yml
@@ -0,0 +1,3 @@
+features:
+- name: constraint-validation
+  files: "**"
diff --git a/testing/web-platform/tests/html/semantics/forms/constraints/form-validation-validity-textarea-defaultValue.html b/testing/web-platform/tests/html/semantics/forms/constraints/form-validation-validity-textarea-defaultValue.html
new file mode 100644
index 0000000000..55276116ad
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/constraints/form-validation-validity-textarea-defaultValue.html
@@ -0,0 +1,98 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>textarea validation behavior</title>
+<link rel="author" href="mailto:masonf@chromium.org">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#suffering-from-being-too-short">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-constraint-validation-api">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+
+<textarea id=t1 minlength=5 required></textarea>
+<textarea id=t2 minlength=5 required>a</textarea>
+<textarea id=t3 required>a</textarea>
+<textarea id=t4>a</textarea>
+<script>
+test(() => {
+  const emptyMinlength = document.getElementById('t1');
+  const nonEmptyMinlength = document.getElementById('t2');
+  const nonEmptyRequired = document.getElementById('t3');
+  const nonEmptyNonRequired = document.getElementById('t4');
+  assert_false(emptyMinlength.validity.valid,'Empty textareas with constraints will validate');
+  assert_true(nonEmptyMinlength.validity.valid,'Non-empty textareas with constraints will *not* validate');
+  assert_true(nonEmptyRequired.validity.valid,'Textareas without constraints will validate');
+  assert_true(nonEmptyNonRequired.validity.valid,'Textareas without constraints will validate');
+  [t1,t2,t3,t4].forEach(t => t.remove());
+},'Default validity based on emptiness');
+</script>
+
+<textarea id=t5 minlength=5 required></textarea>
+<script>
+promise_test(async () => {
+  const textarea = document.getElementById('t5');
+  document.querySelector('#t1');
+  assert_false(textarea.validity.valid,'By default, this textarea will validate (and fail) because it started empty');
+  textarea.defaultValue = 'abc';
+  assert_true(textarea.validity.valid,'Programmatically setting defaultValue is not a user edit - automatically valid');
+  textarea.replaceChildren('abcd');
+  assert_true(textarea.validity.valid,'Programmatically replacing children is not a user edit - automatically valid');
+  textarea.defaultValue = 'abcde';
+  assert_true(textarea.validity.valid,'Still valid');
+  textarea.remove();
+},'Setting textarea.defaultValue should not trigger validation');
+</script>
+
+<textarea id=t6 minlength=5 required></textarea>
+<script>
+promise_test(async () => {
+  const textarea = document.getElementById('t6');
+  assert_false(textarea.validity.valid,'By default, this textarea will validate (and fail) because it started empty');
+  await test_driver.send_keys(textarea, "abc");
+  assert_false(textarea.validity.valid,'Keystrokes should trigger validation, which will fail (length 3)');
+  await test_driver.send_keys(textarea, "de");
+  assert_equals(textarea.value,"abcde");
+  assert_true(textarea.validity.valid,'Now valid');
+  textarea.remove();
+},'User keystrokes should trigger validation');
+</script>
+
+<textarea id=t7 minlength=5 required></textarea>
+<script>
+promise_test(async () => {
+  const textarea = document.getElementById('t7');
+  textarea.addEventListener('input', (e) => {
+    e.target.defaultValue = e.target.value;
+  });
+  assert_false(textarea.validity.valid,'By default, this textarea will validate (and fail) because it started empty');
+  await test_driver.send_keys(textarea, "abc");
+  assert_equals(textarea.value,"abc");
+  assert_false(textarea.validity.valid,'Still invalid with 3 characters');
+  await test_driver.send_keys(textarea, "de");
+  assert_equals(textarea.value,"abcde");
+  assert_true(textarea.validity.valid,'With 5 characters, now valid');
+  textarea.remove();
+},'Setting textarea.defaultValue from the input event handler should trigger validation');
+</script>
+
+<textarea id=t8 minlength=5 required></textarea>
+<script>
+promise_test(async () => {
+  const textarea = document.getElementById('t8');
+  textarea.addEventListener('input', (e) => {
+    e.target.replaceChildren(e.target.value);
+  });
+  assert_false(textarea.validity.valid,'By default, this textarea will validate (and fail) because it started empty');
+  await test_driver.send_keys(textarea, "abc");
+  assert_equals(textarea.value,"abc");
+  assert_false(textarea.validity.valid,'Still invalid with 3 characters');
+  await test_driver.send_keys(textarea, "de");
+  assert_equals(textarea.value,"abcde");
+  assert_true(textarea.validity.valid,'With 5 characters, now valid');
+  textarea.remove();
+},'Calling textarea.replaceChildren() from the input event handler should trigger validation');
+</script>
+
+<style>
+  :invalid { background-color: rgb(248, 203, 203); }
+</style>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-button-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-button-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..f5a2aeaf4f
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-button-element/WEB_FEATURES.yml
@@ -0,0 +1,10 @@
+features:
+- name: constraint-validation
+  files:
+  - button-checkvalidity.html
+  - button-setcustomvalidity.html
+  - button-validation.html
+  - button-validationmessage.html
+  - button-validity.html
+  - button-willvalidate-readonly-attribute.html
+  - button-willvalidate.html
diff --git a/testing/web-platform/tests/html/semantics/forms/the-fieldset-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-fieldset-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..912cb47c6d
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-fieldset-element/WEB_FEATURES.yml
@@ -0,0 +1,8 @@
+features:
+- name: constraint-validation
+  files:
+  - fieldset-checkvalidity.html
+  - fieldset-setcustomvalidity.html
+  - fieldset-validationmessage.html
+  - fieldset-validity.html
+  - fieldset-willvalidate.html
diff --git a/testing/web-platform/tests/html/semantics/forms/the-form-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-form-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..04c20cb5ec
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-form-element/WEB_FEATURES.yml
@@ -0,0 +1,4 @@
+features:
+- name: constraint-validation
+  files:
+  - form-checkvalidity.html
diff --git a/testing/web-platform/tests/html/semantics/forms/the-input-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-input-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..4957615f24
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-input-element/WEB_FEATURES.yml
@@ -0,0 +1,11 @@
+features:
+- name: constraint-validation
+  files:
+  - input-checkvalidity.html
+  - input-setcustomvalidity.html
+  - input-validationmessage.html
+  - input-validity.html
+  - input-willvalidate.html
+- name: show-picker-input
+  files:
+  - show-picker-*
diff --git a/testing/web-platform/tests/html/semantics/forms/the-input-element/input-stepdown-02.html b/testing/web-platform/tests/html/semantics/forms/the-input-element/input-stepdown-02.html
new file mode 100644
index 0000000000..db71d11009
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-input-element/input-stepdown-02.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<title>Input Step Down</title>
+
+<link rel="help" href="https://html.spec.whatwg.org/multipage/input.html#dom-input-stepup">
+
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<input type='number' id='input'>
+
+<script>
+  const input = document.getElementById("input");
+
+  function testStepDown(initialValue, minValue, expectedValue) {
+    input.value = initialValue;
+    input.min = minValue;
+
+    input.stepDown();
+
+    assert_equals(input.value, expectedValue);
+  }
+
+  const tests = [
+    { initialValue: '', minValue: '', expectedValue: '-1', description: 'stepDown() on input with no initial or min values' },
+    { initialValue: '', minValue: '7', expectedValue: '7', description: 'stepDown() on input with no initial value and positive min value' },
+    { initialValue: '', minValue: '-7', expectedValue: '-1', description: 'stepDown() on input with no initial value and negative min value' },
+    { initialValue: '7', minValue: '7', expectedValue: '7', description: 'stepDown() on input with initial value equal to min value' },
+    { initialValue: '3', minValue: '7', expectedValue: '3', description: 'stepDown() on input with initial value less than min value' },
+    { initialValue: '10', minValue: '7', expectedValue: '9', description: 'stepDown() on input with initial value greater than min value' },
+  ];
+
+  for(const t of tests) {
+    test(()=>{
+      testStepDown(
+        t.initialValue,
+        t.minValue,
+        t.expectedValue
+      );
+    },
+    t.description);
+  }
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-output-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-output-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..2f7f8e8cc2
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-output-element/WEB_FEATURES.yml
@@ -0,0 +1,5 @@
+features:
+- name: constraint-validation
+  files:
+  - output-setcustomvalidity.html
+  - output-validity.html
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-select-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..9695c95294
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/WEB_FEATURES.yml
@@ -0,0 +1,9 @@
+features:
+- name: constraint-validation
+  files:
+  - select-setcustomvalidity.html
+  - select-validity.html
+  - select-willvalidate-readonly-attribute.html
+- name: show-picker-select
+  files:
+  - show-picker-*
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist-ref.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist-ref.html
new file mode 100644
index 0000000000..87918b6a92
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist-ref.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html class=reftest-wait>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+
+<select>
+  <option>one</option>
+  <hr>
+  <option>two</option>
+</select>
+
+<script>
+(async () => {
+  await test_driver.click(document.querySelector('select'));
+  document.documentElement.classList.remove('reftest-wait');
+})();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist.tentative.html
new file mode 100644
index 0000000000..a968c6a164
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/native-popup-with-datalist.tentative.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html class=reftest-wait>
+<link rel=author href="mailto:jarhar@chromium.org">
+<link rel=help href="https://github.com/whatwg/html/issues/9799">
+<link rel=match href="native-popup-with-datalist-ref.html">
+<link rel=assert title="The native popup of a select should show options descending from datalists">
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+
+<select>
+  <datalist>
+    <div>
+      <option>one</option>
+      <hr>
+      <option>two</option>
+    </div>
+  </datalist>
+</select>
+
+<script>
+(async () => {
+  await test_driver.click(document.querySelector('select'));
+  document.documentElement.classList.remove('reftest-wait');
+})();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/nested-options.tenative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/nested-options.tenative.html
new file mode 100644
index 0000000000..7e89a5ad42
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/nested-options.tenative.html
@@ -0,0 +1,46 @@
+<!DOCTYPE html>
+<link rel=author href="mailto:jarhar@chromium.org">
+<link rel=help href="https://bugs.chromium.org/p/chromium/issues/detail?id=1422275">
+<link rel=help href="https://chromium-review.googlesource.com/c/chromium/src/+/5441435/1#message-cd8841d92a672a0276ab536dfaf3a20e93d5e6e3">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+
+<select>
+  <datalist>
+    <option id=o1>
+      parent
+      <option id=o2>child</option>
+</option>
+  </datalist>
+</select>
+
+<script>
+const select = document.querySelector('select');
+
+test(() => {
+  assert_equals(select.innerHTML, `
+  <datalist>
+    <option id="o1">
+      parent
+      </option><option id="o2">child</option>
+
+  </datalist>
+`);
+}, 'The HTML parser should disallow nested options in select datalist.');
+
+// Manually nest the <options> anyway for the following tests.
+o1.appendChild(o2);
+
+test(() => {
+  assert_equals(select.options.length, 2, 'select.options.length');
+  assert_equals(select.options[0], o1, 'select.options[0]');
+  assert_equals(select.options[1], o2, 'select.options[1]');
+}, 'Nested <options> should be listed in <select> IDLs.');
+
+promise_test(async () => {
+  await test_driver.bless();
+  select.showPicker();
+}, 'Showing the popup with nested <option>s should not crash.');
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/select-reset-non-interoperable-styles.css b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/select-reset-non-interoperable-styles.css
deleted file mode 100644
index d2b9d9df26..0000000000
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/select-reset-non-interoperable-styles.css
+++ /dev/null
@@ -1,5 +0,0 @@
-/* TODO(crbug.com/1511354): linux.css sets background-color on select, consider
- * removing it. */
-select {
-  background-color: Field;
-}
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/stylable-select-styles.css b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/stylable-select-styles.css
index 042de838d1..5ee317d61a 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/stylable-select-styles.css
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/resources/stylable-select-styles.css
@@ -1,9 +1,6 @@
 /* These are UA styles for select and stylable select. */
 
 .stylable-select-container {
-  background-color: Field;
-  border: 1px solid rgba(0, 0, 0, 0);
-  border-radius: 0;
   box-sizing: border-box;
   display: inline-block;
 }
@@ -14,7 +11,8 @@
   overflow: auto;
   border: 1px solid rgba(0, 0, 0, 0.15);
   border-radius: 0.25em;
-  padding: 0.25em 0;
+  padding-block: 0.25em;
+  padding-inline: 0;
   background-color: Field;
   margin: 0;
   inset: auto;
@@ -35,3 +33,46 @@
   padding: 0px 2px 1px;
   white-space: nowrap;
 }
+
+.stylable-select-button {
+  color: FieldText;
+  background-color: Field;
+  appearance: none;
+  padding: 0.25em;
+  border: 1px solid ButtonBorder;
+  cursor: default;
+  text-align: inherit;
+  display: inline-flex;
+  flex-grow: 1;
+  flex-shrink: 1;
+  align-items: center;
+  overflow-x: hidden;
+  overflow-y: hidden;
+}
+
+.stylable-select-button-icon {
+  background-image: url(data:image/svg+xml,%3Csvg%20width%3D%2220%22%20height%3D%2214%22%20viewBox%3D%220%200%2020%2016%22%20fill%3D%22none%22%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%3E%3Cpath%20d%3D%22M4%206%20L10%2012%20L%2016%206%22%20stroke%3D%22WindowText%22%20stroke-width%3D%223%22%20stroke-linejoin%3D%22round%22%2F%3E%3C%2Fsvg%3E);
+  background-origin: content-box;
+  background-repeat: no-repeat;
+  background-size: contain;
+  opacity: 1;
+  outline: none;
+  margin-inline-start: 0.25em;
+  padding-block: 2px;
+  padding-inline: 3px;
+  block-size: 1.0em;
+  inline-size: 1.2em;
+  min-inline-size: 1.2em;
+  max-inline-size: 1.2em;
+  display: block;
+}
+
+.stylable-select-selectedoption {
+  color: inherit;
+  min-inline-size: 0px;
+  max-block-size: 100%;
+  flex-grow: 1;
+  flex-shrink: 1;
+  overflow: hidden;
+  display: inline;
+}
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist-ref.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist-ref.html
new file mode 100644
index 0000000000..10c966a107
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist-ref.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<link rel=stylesheet href="resources/stylable-select-styles.css">
+
+<div id=container class=stylable-select-container>
+  <button>one</button>
+  <div id=popover popover=auto anchor=container class=stylable-select-datalist>
+    <div class=stylable-select-option>one</div>
+    <div class=stylable-select-option>two</div>
+  </div>
+</div>
+
+<script>
+document.getElementById('popover').showPopover();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist.tentative.html
index 94d7fd53b3..aaceabcf05 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-custom-button-no-datalist.tentative.html
@@ -2,8 +2,7 @@
 <html class=reftest-wait>
 <link rel=author href="mailto:jarhar@chromium.org">
 <link rel=help href="https://github.com/whatwg/html/issues/9799">
-<link rel=match href="select-appearance-no-button-custom-datalist-ref.html">
-<link rel=stylesheet href="resources/select-reset-non-interoperable-styles.css">
+<link rel=match href="select-appearance-custom-button-no-datalist-ref.html">
 <script src="/resources/testdriver.js"></script>
 <script src="/resources/testdriver-vendor.js"></script>
 
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist-ref.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist-ref.html
deleted file mode 100644
index 8e5eadaf57..0000000000
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist-ref.html
+++ /dev/null
@@ -1,14 +0,0 @@
-<!DOCTYPE html>
-<link rel=stylesheet href="resources/stylable-select-styles.css">
-
-<div id=container class=stylable-select-container>
-  <button popovertarget=popover id=button>one</button>
-  <div id=popover popover=auto anchor=container class=stylable-select-datalist>
-    <div class=stylable-select-option>one</div>
-    <div class=stylable-select-option>two</div>
-  </div>
-</div>
-
-<script>
-document.getElementById('popover').showPopover();
-</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist.tentative.html
index 87425cf7a3..cc8a4c60bd 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-custom-datalist.tentative.html
@@ -2,8 +2,7 @@
 <html class=reftest-wait>
 <link rel=author href="mailto:jarhar@chromium.org">
 <link rel=help href="https://github.com/whatwg/html/issues/9799">
-<link rel=match href="select-appearance-no-button-custom-datalist-ref.html">
-<link rel=stylesheet href="resources/select-reset-non-interoperable-styles.css">
+<link rel=match href="select-appearance-no-button-no-datalist-ref.html">
 <script src="/resources/testdriver.js"></script>
 <script src="/resources/testdriver-vendor.js"></script>
 
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist-ref.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist-ref.html
new file mode 100644
index 0000000000..3c6e9416b0
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist-ref.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<link rel=stylesheet href="resources/stylable-select-styles.css">
+
+<div id=container class=stylable-select-container>
+  <button class=stylable-select-button popovertarget=popover id=button>
+    <span class=stylable-select-selectedoption>one</span>
+    <div class=stylable-select-button-icon></div>
+  </button>
+  <div id=popover popover=auto anchor=container class=stylable-select-datalist>
+    <div class=stylable-select-option>one</div>
+    <div class=stylable-select-option>two</div>
+  </div>
+</div>
+
+<script>
+document.getElementById('popover').showPopover();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist.tentative.html
index b2a6b5a6d3..29261b7f25 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-no-button-no-datalist.tentative.html
@@ -2,8 +2,7 @@
 <html class=reftest-wait>
 <link rel=author href="mailto:jarhar@chromium.org">
 <link rel=help href="https://github.com/whatwg/html/issues/9799">
-<link rel=match href="select-appearance-no-button-custom-datalist-ref.html">
-<link rel=stylesheet href="resources/select-reset-non-interoperable-styles.css">
+<link rel=match href="select-appearance-no-button-no-datalist-ref.html">
 <script src="/resources/testdriver.js"></script>
 <script src="/resources/testdriver-vendor.js"></script>
 
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr-ref.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr-ref.html
new file mode 100644
index 0000000000..8b7e6402fb
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr-ref.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<link rel=stylesheet href="resources/stylable-select-styles.css">
+
+<style>
+html {
+  writing-mode: vertical-lr;
+}
+</style>
+
+<div id=container class=stylable-select-container>
+  <button class=stylable-select-button popovertarget=popover id=button>
+    <span class=stylable-select-selectedoption>one</span>
+    <div class=stylable-select-button-icon></div>
+  </button>
+  <div id=popover popover=auto anchor=container class=stylable-select-datalist>
+    <div class=stylable-select-option>one</div>
+    <div class=stylable-select-option>two</div>
+  </div>
+</div>
+
+<script>
+document.getElementById('popover').showPopover();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr.tentative.html
new file mode 100644
index 0000000000..2f8a6aa886
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-lr.tentative.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html class=reftest-wait>
+<link rel=author href="mailto:jarhar@chromium.org">
+<link rel=help href="https://github.com/whatwg/html/issues/9799">
+<link rel=match href="select-appearance-writing-mode-vertical-lr-ref.html">
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+
+<style>
+html {
+  writing-mode: vertical-lr;
+}
+select {
+  appearance: base-select;
+}
+</style>
+
+<select>
+  <option>one</option>
+  <option>two</option>
+</select>
+
+<script>
+(async () => {
+  await test_driver.bless();
+  document.querySelector('select').showPicker();
+  document.documentElement.classList.remove('reftest-wait');
+})();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl-ref.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl-ref.html
new file mode 100644
index 0000000000..158807ba58
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl-ref.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<link rel=stylesheet href="resources/stylable-select-styles.css">
+
+<style>
+html {
+  writing-mode: vertical-rl;
+}
+</style>
+
+<div id=container class=stylable-select-container>
+  <button class=stylable-select-button popovertarget=popover id=button>
+    <span class=stylable-select-selectedoption>one</span>
+    <div class=stylable-select-button-icon></div>
+  </button>
+  <div id=popover popover=auto anchor=container class=stylable-select-datalist>
+    <div class=stylable-select-option>one</div>
+    <div class=stylable-select-option>two</div>
+  </div>
+</div>
+
+<script>
+document.getElementById('popover').showPopover();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl.tentative.html
new file mode 100644
index 0000000000..c2ea647be9
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-appearance-writing-mode-vertical-rl.tentative.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html class=reftest-wait>
+<link rel=author href="mailto:jarhar@chromium.org">
+<link rel=help href="https://github.com/whatwg/html/issues/9799">
+<link rel=match href="select-appearance-writing-mode-vertical-rl-ref.html">
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+
+<style>
+html {
+  writing-mode: vertical-rl;
+}
+select {
+  appearance: base-select;
+}
+</style>
+
+<select>
+  <option>one</option>
+  <option>two</option>
+</select>
+
+<script>
+(async () => {
+  await test_driver.bless();
+  document.querySelector('select').showPicker();
+  document.documentElement.classList.remove('reftest-wait');
+})();
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist-invalidation.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist-invalidation.tentative.html
index b6d85ac90a..822a63e104 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist-invalidation.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist-invalidation.tentative.html
@@ -3,7 +3,6 @@
 <link rel=author href="mailto:jarhar@chromium.org">
 <link rel=help href="https://github.com/whatwg/html/issues/9799">
 <link rel=match href="select-child-button-and-datalist-ref.html">
-<link rel=stylesheet href="resources/select-reset-non-interoperable-styles.css">
 
 <style>
 .blue {
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist.tentative.html
index 610861aad8..9b2f53df28 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-child-button-and-datalist.tentative.html
@@ -2,7 +2,6 @@
 <link rel=author href="mailto:jarhar@chromium.org">
 <link rel=help href="https://github.com/whatwg/html/issues/9799">
 <link rel=match href="select-child-button-and-datalist-ref.html">
-<link rel=stylesheet href="resources/select-reset-non-interoperable-styles.css">
 
 <style>
 .blue {
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-datalist-popover-behavior.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-datalist-popover-behavior.tentative.html
new file mode 100644
index 0000000000..caea2a2f8d
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-datalist-popover-behavior.tentative.html
@@ -0,0 +1,75 @@
+<!DOCTYPE html>
+<link rel=author href="mailto:jarhar@chromium.org">
+<link rel=help href="https://bugs.chromium.org/p/chromium/issues/detail?id=1422275">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+
+<select style="appearance:base-select">
+  <button type=popover>button</button>
+  <datalist>
+    <option class=one>one</option>
+    <option class=two>two</option>
+  </datalist>
+</select>
+
+<script>
+const select = document.querySelector('select');
+const datalist = document.querySelector('datalist');
+const firstOption = document.querySelector('option.one');
+const secondOption = document.querySelector('option.two');
+
+promise_test(async () => {
+  datalist.showPopover();
+  assert_true(datalist.matches(':popover-open'));
+  datalist.hidePopover();
+  assert_false(datalist.matches(':popover-open'));
+}, 'showPopover and hidePopover should work on the select datalist.');
+
+promise_test(async () => {
+  await test_driver.bless();
+  select.showPicker();
+  assert_true(datalist.matches(':popover-open'));
+  datalist.hidePopover();
+}, 'showPicker should show the select datalist.');
+
+promise_test(async () => {
+  datalist.addEventListener('beforetoggle', event => {
+    event.preventDefault();
+  }, {once: true});
+  await test_driver.bless();
+  select.showPicker();
+  assert_false(datalist.matches(':popover-open'));
+}, 'preventDefault on beforetoggle should prevent the datalist from showing.');
+
+promise_test(async () => {
+  select.remove();
+  assert_throws_dom('InvalidStateError', () => datalist.showPopover());
+  assert_false(datalist.matches(':popover-open'));
+  document.body.appendChild(select);
+}, 'showPopover on a disconnected datalist should throw an exception.');
+
+promise_test(async () => {
+  datalist.addEventListener('beforetoggle', event => {
+    select.remove();
+  }, {once: true});
+  await test_driver.bless();
+  select.showPicker();
+  assert_false(!!select.parentNode);
+  assert_false(datalist.matches(':popover-open'));
+  document.body.appendChild(select);
+}, 'Disconnecting while internally showing the datalist should not crash or show the popover.');
+
+promise_test(async () => {
+  datalist.showPopover();
+  datalist.addEventListener('beforetoggle', event => {
+    select.remove();
+  }, {once: true});
+  await test_driver.click(secondOption);
+  assert_false(!!select.parentNode);
+  assert_false(datalist.matches(':popover-open'));
+  document.body.appendChild(select);
+}, 'Disconnecting while internally hiding the datalist should not crash.');
+</script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-keyboard-behavior.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-keyboard-behavior.tentative.html
index 2fb11ba68b..8b06212169 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-keyboard-behavior.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/stylable-select/select-keyboard-behavior.tentative.html
@@ -1,4 +1,5 @@
 <!DOCTYPE html>
+<meta name=timeout content=long>
 <link rel=author href="mailto:jarhar@chromium.org">
 <link rel=help href="https://bugs.chromium.org/p/chromium/issues/detail?id=1422275">
 <link rel=help href="https://github.com/openui/open-ui/issues/433#issuecomment-1452461404">
@@ -68,6 +69,7 @@ for (const id of ['defaultbutton-defaultdatalist',
 
   async function closeListbox() {
     await test_driver.click(select);
+    await new Promise(requestAnimationFrame);
   }
 
   function addCloseCleanup(t) {
@@ -96,6 +98,7 @@ for (const id of ['defaultbutton-defaultdatalist',
     assert_false(select.matches(':open'),
       'The select should initially be closed.');
     await test_driver.send_keys(document.activeElement, Space);
+    await new Promise(requestAnimationFrame);
     assert_true(select.matches(':open'),
       'The select should be open after pressing space.');
   }, `${id}: When the listbox is closed, spacebar should open the listbox.`);
@@ -108,6 +111,7 @@ for (const id of ['defaultbutton-defaultdatalist',
       'The select should initially be closed.');
 
     await test_driver.send_keys(document.activeElement, ArrowLeft);
+    await new Promise(requestAnimationFrame);
     assert_true(select.matches(':open'),
       'Arrow left should open the listbox.');
     assert_equals(select.value, 'two',
@@ -115,6 +119,7 @@ for (const id of ['defaultbutton-defaultdatalist',
     await closeListbox();
 
     await test_driver.send_keys(document.activeElement, ArrowUp);
+    await new Promise(requestAnimationFrame);
     assert_true(select.matches(':open'),
       'Arrow up should open the listbox.');
     assert_equals(select.value, 'two',
@@ -122,6 +127,7 @@ for (const id of ['defaultbutton-defaultdatalist',
     await closeListbox();
 
     await test_driver.send_keys(document.activeElement, ArrowRight);
+    await new Promise(requestAnimationFrame);
     assert_true(select.matches(':open'),
       'Arrow right should open the listbox.');
     assert_equals(select.value, 'two',
@@ -129,6 +135,7 @@ for (const id of ['defaultbutton-defaultdatalist',
     await closeListbox();
 
     await test_driver.send_keys(document.activeElement, ArrowDown);
+    await new Promise(requestAnimationFrame);
     assert_true(select.matches(':open'),
       'Arrow down should open the listbox.');
     assert_equals(select.value, 'two',
@@ -147,6 +154,7 @@ for (const id of ['defaultbutton-defaultdatalist',
     } else {
       await test_driver.send_keys(select, Enter);
     }
+    await new Promise(requestAnimationFrame);
     assert_false(select.matches(':open'),
       'Enter should not open the listbox when outside a form.');
 
@@ -161,6 +169,7 @@ for (const id of ['defaultbutton-defaultdatalist',
     } else {
       await test_driver.send_keys(select, Enter);
     }
+    await new Promise(requestAnimationFrame);
     assert_true(formWasSubmitted,
       'Enter should submit the form when the listbox is closed.');
     assert_false(select.matches(':open'),
@@ -175,30 +184,35 @@ for (const id of ['defaultbutton-defaultdatalist',
 
     select.value = 'two';
     await test_driver.click(select);
+    await new Promise(requestAnimationFrame);
     assert_true(select.matches(':open'),
       'The select should open when clicked.');
     assert_equals(document.activeElement, optionTwo,
       'The selected option should receive initial focus.');
 
     await test_driver.send_keys(document.activeElement, ArrowDown);
+    await new Promise(requestAnimationFrame);
     assert_equals(document.activeElement, optionThree,
       'The next option should receive focus when the down arrow key is pressed.');
     assert_equals(select.value, 'two',
       'The selects value should not change when focusing another option.');
 
     await test_driver.send_keys(document.activeElement, ArrowUp);
+    await new Promise(requestAnimationFrame);
     assert_equals(document.activeElement, optionTwo,
       'The previous option should receive focus when the up arrow key is pressed.');
     assert_equals(select.value, 'two',
       'The selects value should not change when focusing another option.');
 
     await test_driver.send_keys(document.activeElement, ArrowUp);
+    await new Promise(requestAnimationFrame);
     assert_equals(document.activeElement, optionOne,
       'The first option should be selected.');
     assert_equals(select.value, 'two',
       'The selects value should not change when focusing another option.');
 
     await test_driver.send_keys(document.activeElement, Enter);
+    await new Promise(requestAnimationFrame);
     assert_false(select.matches(':open'),
       'The listbox should be closed after pressing enter.');
     assert_equals(select.value, 'one',
diff --git a/testing/web-platform/tests/html/semantics/forms/the-selectlist-element/selectlist-option-arbitrary-content-displayed.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-selectlist-element/selectlist-option-arbitrary-content-displayed.tentative.html
index 2d51002fb2..8c620bacca 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-selectlist-element/selectlist-option-arbitrary-content-displayed.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-selectlist-element/selectlist-option-arbitrary-content-displayed.tentative.html
@@ -3,6 +3,8 @@
 <title>HTMLSelectListElement Test: option arbitrary content displayed</title>
 <link rel="author" title="Ionel Popescu" href="mailto:iopopesc@microsoft.com">
 <link rel=match href="selectlist-option-arbitrary-content-displayed-ref.tentative.html">
+<!-- Tolerate slight differences in the shadow gradient. -->
+<meta name=fuzzy content="maxDifference=0-1;totalPixels=0-200">
 <link rel="stylesheet" href="/fonts/ahem.css">
 <script src="/resources/testdriver.js"></script>
 <script src="/resources/testdriver-actions.js"></script>
diff --git a/testing/web-platform/tests/html/semantics/forms/the-textarea-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/forms/the-textarea-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..14479d4bb3
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/forms/the-textarea-element/WEB_FEATURES.yml
@@ -0,0 +1,6 @@
+features:
+- name: constraint-validation
+  files:
+  - textarea-setcustomvalidity.html
+  - textarea-validity-clone.html
+  - textarea-validity-valueMissing-inside-datalist.html
diff --git a/testing/web-platform/tests/html/semantics/interactive-elements/the-details-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/interactive-elements/the-details-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..be3924a26a
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/interactive-elements/the-details-element/WEB_FEATURES.yml
@@ -0,0 +1,4 @@
+features:
+- name: details-name
+  files:
+  - name-attribute.html
diff --git a/testing/web-platform/tests/html/semantics/invokers/interesttarget-anchor-event-dispatch.tentative.html b/testing/web-platform/tests/html/semantics/invokers/interesttarget-anchor-event-dispatch.tentative.html
new file mode 100644
index 0000000000..b5a481ae08
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/invokers/interesttarget-anchor-event-dispatch.tentative.html
@@ -0,0 +1,47 @@
+<!doctype html>
+<meta charset="utf-8" />
+<meta name="author" title="Keith Cirkel" href="mailto:keithamus@github.com" />
+<meta name="author" title="Luke Warlow" href="mailto:lwarlow@igalia.com" />
+<link rel="help" href="https://open-ui.org/components/invokers.explainer/" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/invoker-utils.js"></script>
+
+<div id="interestee"></div>
+<a href="/" id="interestanchor" interesttarget="interestee">Anchor</a>
+<button id="otherbutton">Other Button</button>
+
+<script>
+  promise_test(async function (t) {
+    t.add_cleanup(() => otherbutton.focus());
+    let event = null;
+    interestee.addEventListener("interest", (e) => (event = e), { once: true });
+    interestanchor.focus();
+    assert_true(event instanceof InterestEvent, "event is InterestEvent");
+    assert_equals(event.type, "interest", "type");
+    assert_equals(event.bubbles, false, "bubbles");
+    assert_equals(event.composed, true, "composed");
+    assert_equals(event.isTrusted, true, "isTrusted");
+    assert_equals(event.action, "", "action");
+    assert_equals(event.target, interestee, "target");
+    assert_equals(event.invoker, interestanchor, "invoker");
+  }, "InterestEvent dispatches on anchor focus");
+
+  promise_test(async function (t) {
+    t.add_cleanup(() => otherbutton.focus());
+    let event = null;
+    interestee.addEventListener("interest", (e) => (event = e), { once: true });
+    await hoverOver(interestanchor);
+    assert_true(event instanceof InterestEvent, "event is InterestEvent");
+    assert_equals(event.type, "interest", "type");
+    assert_equals(event.bubbles, false, "bubbles");
+    assert_equals(event.composed, true, "composed");
+    assert_equals(event.isTrusted, true, "isTrusted");
+    assert_equals(event.action, "", "action");
+    assert_equals(event.target, interestee, "target");
+    assert_equals(event.invoker, interestanchor, "invoker");
+  }, "InterestEvent dispatches on anchor hover");
+</script>
diff --git a/testing/web-platform/tests/html/semantics/invokers/interesttarget-area-event-dispatch.tentative.html b/testing/web-platform/tests/html/semantics/invokers/interesttarget-area-event-dispatch.tentative.html
new file mode 100644
index 0000000000..358acbb73a
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/invokers/interesttarget-area-event-dispatch.tentative.html
@@ -0,0 +1,50 @@
+<!doctype html>
+<meta charset="utf-8" />
+<meta name="author" title="Keith Cirkel" href="mailto:keithamus@github.com" />
+<meta name="author" title="Luke Warlow" href="mailto:lwarlow@igalia.com" />
+<link rel="help" href="https://open-ui.org/components/invokers.explainer/" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/invoker-utils.js"></script>
+
+<div id="interestee"></div>
+<map id="map">
+  <area href="/" shape="default" id="interestarea" interesttarget="interestee">
+</map>
+<img src="/images/blue.png" usemap="#map">
+<button id="otherbutton">Other Button</button>
+
+<script>
+  promise_test(async function (t) {
+    t.add_cleanup(() => otherbutton.focus());
+    let event = null;
+    interestee.addEventListener("interest", (e) => (event = e), { once: true });
+    interestarea.focus();
+    assert_true(event instanceof InterestEvent, "event is InterestEvent");
+    assert_equals(event.type, "interest", "type");
+    assert_equals(event.bubbles, false, "bubbles");
+    assert_equals(event.composed, true, "composed");
+    assert_equals(event.isTrusted, true, "isTrusted");
+    assert_equals(event.action, "", "action");
+    assert_equals(event.target, interestee, "target");
+    assert_equals(event.invoker, interestarea, "invoker");
+  }, "InterestEvent dispatches on area focus");
+
+  promise_test(async function (t) {
+    t.add_cleanup(() => otherbutton.focus());
+    let event = null;
+    interestee.addEventListener("interest", (e) => (event = e), { once: true });
+    await hoverOver(interestarea);
+    assert_true(event instanceof InterestEvent, "event is InterestEvent");
+    assert_equals(event.type, "interest", "type");
+    assert_equals(event.bubbles, false, "bubbles");
+    assert_equals(event.composed, true, "composed");
+    assert_equals(event.isTrusted, true, "isTrusted");
+    assert_equals(event.action, "", "action");
+    assert_equals(event.target, interestee, "target");
+    assert_equals(event.invoker, interestarea, "invoker");
+  }, "InterestEvent dispatches on area hover");
+</script>
diff --git a/testing/web-platform/tests/html/semantics/invokers/interesttarget-button-event-dispatch.tentative.html b/testing/web-platform/tests/html/semantics/invokers/interesttarget-button-event-dispatch.tentative.html
index 7fdfdfaa70..69126dbe14 100644
--- a/testing/web-platform/tests/html/semantics/invokers/interesttarget-button-event-dispatch.tentative.html
+++ b/testing/web-platform/tests/html/semantics/invokers/interesttarget-button-event-dispatch.tentative.html
@@ -12,7 +12,6 @@
 
 <div id="interestee"></div>
 <button id="interestbutton" interesttarget="interestee">Button</button>
-<a href="/" id="interestanchor" interesttarget="interestee">Anchor</a>
 <button id="otherbutton">Other Button</button>
 
 <script>
@@ -46,36 +45,6 @@
     assert_equals(event.invoker, interestbutton, "invoker");
   }, "InterestEvent dispatches on button hover");
 
-  promise_test(async function (t) {
-    t.add_cleanup(() => otherbutton.focus());
-    let event = null;
-    interestee.addEventListener("interest", (e) => (event = e), { once: true });
-    interestanchor.focus();
-    assert_true(event instanceof InterestEvent, "event is InterestEvent");
-    assert_equals(event.type, "interest", "type");
-    assert_equals(event.bubbles, false, "bubbles");
-    assert_equals(event.composed, true, "composed");
-    assert_equals(event.isTrusted, true, "isTrusted");
-    assert_equals(event.action, "", "action");
-    assert_equals(event.target, interestee, "target");
-    assert_equals(event.invoker, interestanchor, "invoker");
-  }, "InterestEvent dispatches on anchor focus");
-
-  promise_test(async function (t) {
-    t.add_cleanup(() => otherbutton.focus());
-    let event = null;
-    interestee.addEventListener("interest", (e) => (event = e), { once: true });
-    await hoverOver(interestanchor);
-    assert_true(event instanceof InterestEvent, "event is InterestEvent");
-    assert_equals(event.type, "interest", "type");
-    assert_equals(event.bubbles, false, "bubbles");
-    assert_equals(event.composed, true, "composed");
-    assert_equals(event.isTrusted, true, "isTrusted");
-    assert_equals(event.action, "", "action");
-    assert_equals(event.target, interestee, "target");
-    assert_equals(event.invoker, interestanchor, "invoker");
-  }, "InterestEvent dispatches on anchor hover");
-
   promise_test(async function (t) {
     t.add_cleanup(() => otherbutton.focus());
     let event = null;
diff --git a/testing/web-platform/tests/html/semantics/invokers/interesttarget-svg-a-event-dispatch.tentative.html b/testing/web-platform/tests/html/semantics/invokers/interesttarget-svg-a-event-dispatch.tentative.html
new file mode 100644
index 0000000000..7fb4b1c19d
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/invokers/interesttarget-svg-a-event-dispatch.tentative.html
@@ -0,0 +1,51 @@
+<!doctype html>
+<meta charset="utf-8" />
+<meta name="author" title="Keith Cirkel" href="mailto:keithamus@github.com" />
+<meta name="author" title="Luke Warlow" href="mailto:lwarlow@igalia.com" />
+<link rel="help" href="https://open-ui.org/components/invokers.explainer/" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/invoker-utils.js"></script>
+
+<div id="interestee"></div>
+<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg">
+  <a href="/" id="interestsvga" interesttarget="interestee">
+    <text x="50" y="90">SVG A</text>
+  </a>
+</svg>
+<button id="otherbutton">Other Button</button>
+
+<script>
+  promise_test(async function (t) {
+    t.add_cleanup(() => otherbutton.focus());
+    let event = null;
+    interestee.addEventListener("interest", (e) => (event = e), { once: true });
+    interestsvga.focus();
+    assert_true(event instanceof InterestEvent, "event is InterestEvent");
+    assert_equals(event.type, "interest", "type");
+    assert_equals(event.bubbles, false, "bubbles");
+    assert_equals(event.composed, true, "composed");
+    assert_equals(event.isTrusted, true, "isTrusted");
+    assert_equals(event.action, "", "action");
+    assert_equals(event.target, interestee, "target");
+    assert_equals(event.invoker, interestsvga, "invoker");
+  }, "InterestEvent dispatches on svg a focus");
+
+  promise_test(async function (t) {
+    t.add_cleanup(() => otherbutton.focus());
+    let event = null;
+    interestee.addEventListener("interest", (e) => (event = e), { once: true });
+    await hoverOver(interestsvga);
+    assert_true(event instanceof InterestEvent, "event is InterestEvent");
+    assert_equals(event.type, "interest", "type");
+    assert_equals(event.bubbles, false, "bubbles");
+    assert_equals(event.composed, true, "composed");
+    assert_equals(event.isTrusted, true, "isTrusted");
+    assert_equals(event.action, "", "action");
+    assert_equals(event.target, interestee, "target");
+    assert_equals(event.invoker, interestsvga, "invoker");
+  }, "InterestEvent dispatches on svg a hover");
+</script>
diff --git a/testing/web-platform/tests/html/semantics/invokers/invoketarget-on-input-number.tentative.html b/testing/web-platform/tests/html/semantics/invokers/invoketarget-on-input-number.tentative.html
new file mode 100644
index 0000000000..b06053b9f1
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/invokers/invoketarget-on-input-number.tentative.html
@@ -0,0 +1,78 @@
+<!doctype html>
+<meta charset="utf-8" />
+<meta name="author" title="Luke Warlow" href="mailto:lwarlow@igalia.com" />
+<link rel="help" href="https://open-ui.org/components/invokers.explainer/" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/invoker-utils.js"></script>
+
+<input type="number" id="invokee" value="0">
+<button id="invokerbutton" invoketarget="invokee"></button>
+
+<script>
+  function reset() {
+    invokee.value = 0;
+    invokerbutton.removeAttribute('invokeaction');
+  }
+
+  // stepUp
+
+  promise_test(async function (t) {
+    t.add_cleanup(reset);
+    assert_equals(invokee.valueAsNumber, 0);
+    invokerbutton.setAttribute("invokeaction", "stepup");
+    await clickOn(invokerbutton);
+    assert_equals(invokee.valueAsNumber, 1);
+  }, "invoking number input with stepup action increments value");
+
+  promise_test(async function (t) {
+    t.add_cleanup(reset);
+    assert_equals(invokee.valueAsNumber, 0);
+    invokerbutton.setAttribute("invokeaction", "sTePuP");
+    await clickOn(invokerbutton);
+    assert_equals(invokee.valueAsNumber, 1);
+  }, "invoking number input with stepup action (case-insensitive) increments value");
+
+  promise_test(async function (t) {
+    t.add_cleanup(reset);
+    assert_equals(invokee.valueAsNumber, 0);
+    invokerbutton.setAttribute("invokeaction", "stepup");
+    invokee.addEventListener("invoke", (e) => e.preventDefault(), {
+      once: true,
+    });
+    await clickOn(invokerbutton);
+    assert_equals(invokee.valueAsNumber, 0);
+  }, "invoking number input with stepup action and preventDefault does not increment value");
+
+  // stepDown
+
+  promise_test(async function (t) {
+    t.add_cleanup(reset);
+    assert_equals(invokee.valueAsNumber, 0);
+    invokerbutton.setAttribute("invokeaction", "stepdown");
+    await clickOn(invokerbutton);
+    assert_equals(invokee.valueAsNumber, -1);
+  }, "invoking number input with stepdown action decrements value");
+
+  promise_test(async function (t) {
+    t.add_cleanup(reset);
+    assert_equals(invokee.valueAsNumber, 0);
+    invokerbutton.setAttribute("invokeaction", "sTePdOwN");
+    await clickOn(invokerbutton);
+    assert_equals(invokee.valueAsNumber, -1);
+  }, "invoking number input with stepdown action (case-insensitive) decrements value");
+
+  promise_test(async function (t) {
+    t.add_cleanup(reset);
+    assert_equals(invokee.valueAsNumber, 0);
+    invokerbutton.setAttribute("invokeaction", "stepdown");
+    invokee.addEventListener("invoke", (e) => e.preventDefault(), {
+      once: true,
+    });
+    await clickOn(invokerbutton);
+    assert_equals(invokee.valueAsNumber, 0);
+  }, "invoking number input with stepdown action and preventDefault does not decrement value");
+</script>
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference-expected.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference-expected.html
deleted file mode 100644
index c62ff5b24d..0000000000
--- a/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference-expected.html
+++ /dev/null
@@ -1,35 +0,0 @@
-<!DOCTYPE html>
-<meta charset=utf-8>
-<body>
-  <div>
-    The permission element should have some limits for specific properties:
-    <ul>
-    <li>font-weight is adjusted to be at least 200.</li>
-    <li>font-style should only have "normal" or "italic" values.</li>
-    <li>word-spacing should be at most 0.5 of the font size, and non-negative.</li>
-    <li>letter-spacing should be between -0.05 and 0.2 of the font size.</li>
-    </ul>
-  </div>
-
-<style>
-  #id1 {
-    font-weight: 200;
-    font-style: normal;
-    word-spacing: 0.5em;
-    font-size: 100px;
-    height: auto;
-    width: auto;
-    letter-spacing: 20px;
-  }
-  #id2 {
-    word-spacing: 0em;
-    height: auto;
-    width: auto;
-    font-size: 10px;
-    letter-spacing: -0.5px;
-  }
-</style>
-
-<permission id="id1" type="geolocation">
-<permission id="id2" type="camera">
-</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference.tentative.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference.tentative.html
deleted file mode 100644
index b8337ab87d..0000000000
--- a/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reference.tentative.html
+++ /dev/null
@@ -1,37 +0,0 @@
-<!DOCTYPE html>
-<meta charset=utf-8>
-<link rel="match" href="bounded-css-properties-reference-expected.html">
-<link rel="help" href="https://github.com/WICG/PEPC/blob/main/explainer.md#locking-the-pepc-style">
-<body>
-  <div>
-    The permission element should have some limits for specific properties:
-    <ul>
-    <li>font-weight is adjusted to be at least 200.</li>
-    <li>font-style should only have "normal" or "italic" values.</li>
-    <li>word-spacing should be at most 0.5 of the font size, and non-negative.</li>
-    <li>letter-spacing should be between -0.05 and 0.2 of the font size.</li>
-    </ul>
-  </div>
-
-<style>
-  #id1 {
-    font-weight: 100;
-    font-style: oblique 30deg;
-    word-spacing: 1em;
-    font-size: 100px;
-    height: auto;
-    width: auto;
-    letter-spacing: 25px;
-  }
-  #id2 {
-    word-spacing: -1000px;
-    height: auto;
-    width: auto;
-    font-size: 10px;
-    letter-spacing: -1px;
-  }
-</style>
-
-<permission id="id1" type="geolocation">
-<permission id="id2" type="camera">
-</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest-ref.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest-ref.html
new file mode 100644
index 0000000000..c62ff5b24d
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest-ref.html
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<body>
+  <div>
+    The permission element should have some limits for specific properties:
+    <ul>
+    <li>font-weight is adjusted to be at least 200.</li>
+    <li>font-style should only have "normal" or "italic" values.</li>
+    <li>word-spacing should be at most 0.5 of the font size, and non-negative.</li>
+    <li>letter-spacing should be between -0.05 and 0.2 of the font size.</li>
+    </ul>
+  </div>
+
+<style>
+  #id1 {
+    font-weight: 200;
+    font-style: normal;
+    word-spacing: 0.5em;
+    font-size: 100px;
+    height: auto;
+    width: auto;
+    letter-spacing: 20px;
+  }
+  #id2 {
+    word-spacing: 0em;
+    height: auto;
+    width: auto;
+    font-size: 10px;
+    letter-spacing: -0.5px;
+  }
+</style>
+
+<permission id="id1" type="geolocation">
+<permission id="id2" type="camera">
+</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest.tentative.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest.tentative.html
new file mode 100644
index 0000000000..ad6986f52b
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/bounded-css-properties-reftest.tentative.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<link rel="match" href="bounded-css-properties-reftest-ref.html">
+<link rel="help" href="https://github.com/WICG/PEPC/blob/main/explainer.md#locking-the-pepc-style">
+<body>
+  <div>
+    The permission element should have some limits for specific properties:
+    <ul>
+    <li>font-weight is adjusted to be at least 200.</li>
+    <li>font-style should only have "normal" or "italic" values.</li>
+    <li>word-spacing should be at most 0.5 of the font size, and non-negative.</li>
+    <li>letter-spacing should be between -0.05 and 0.2 of the font size.</li>
+    </ul>
+  </div>
+
+<style>
+  #id1 {
+    font-weight: 100;
+    font-style: oblique 30deg;
+    word-spacing: 1em;
+    font-size: 100px;
+    height: auto;
+    width: auto;
+    letter-spacing: 25px;
+  }
+  #id2 {
+    word-spacing: -1000px;
+    height: auto;
+    width: auto;
+    font-size: 10px;
+    letter-spacing: -1px;
+  }
+</style>
+
+<permission id="id1" type="geolocation">
+<permission id="id2" type="camera">
+</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest-ref.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest-ref.html
new file mode 100644
index 0000000000..b186dd6445
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest-ref.html
@@ -0,0 +1,56 @@
+<!DOCTYPE html>
+<html>
+<meta charset=utf-8>
+<body>
+  <div>
+    The permission element should have some limits for the min/max-width/height:
+    <ul>
+    <li>min-width should be sufficient to fit the element text (depends on user agent implementation)</li>
+    <li>max-width should be at most 3x min-width</li>
+    <li>min-height should be sufficient to fit the element text (1em)</li>
+    <li>max-height should be at most 3x min-height</li>
+    <li>padding-left/top only work with width/height: auto and are at most 5em/1em</li>
+    <li>padding-right/bottom are copied over from padding-left/top in this case</li>
+    </ul>
+  </div>
+
+  <style>
+    #id1 {
+      font-size: 10px;
+      height: 10px;
+      /* width set via JS */
+    }
+    #id2 {
+      font-size: 10px;
+      height: 30px;
+      /* width set via JS */
+    }
+    #id3 {
+      font-size: 10px;
+      height: 30px;
+      color:black;
+      background-color: black;
+
+      /* Used to compute width which will then have the padding
+         artificially added in JS */
+      width: fit-content;
+    }
+  </style>
+
+  <div><permission id="id1" type="geolocation"></div>
+  <div><permission id="id2" type="camera"></div>
+  <div><permission id="id3" type="microphone"></div>
+
+<script>
+  let el = document.getElementById("id1");
+  el.style.width = getComputedStyle(el).minWidth;
+
+  el = document.getElementById("id2");
+  el.style.width = getComputedStyle(el).maxWidth;
+
+  el = document.getElementById("id3");
+  let w = getComputedStyle(el).width;
+  el.style.width = `calc(${w} + 100px)`; // 100px is 2 * 5em;
+</script>
+</body>
+</html>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest.tentative.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest.tentative.html
new file mode 100644
index 0000000000..45ffb633c3
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes-reftest.tentative.html
@@ -0,0 +1,68 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<link rel="match" href="bounded-sizes-reftest-ref.html">
+<link rel="help" href="https://github.com/WICG/PEPC/blob/main/explainer.md#locking-the-pepc-style">
+<body>
+  <div>
+    The permission element should have some limits for the min/max-width/height:
+    <ul>
+    <li>min-width should be sufficient to fit the element text (depends on user agent implementation)</li>
+    <li>max-width should be at most 3x min-width</li>
+    <li>min-height should be sufficient to fit the element text (1em)</li>
+    <li>max-height should be at most 3x min-height</li>
+    <li>padding-left/top only work with width/height: auto and are at most 5em/1em</li>
+    <li>padding-right/bottom are copied over from padding-left/top in this case</li>
+    </ul>
+  </div>
+
+<style>
+  #id1 {
+    font-size: 10px;
+    min-height: 1px;
+    max-height: 100px;
+
+    /* These values are extreme enough that they should be out of bounds for any implementation */
+    min-width: 10px;
+    max-width: 1000px;
+
+    /* This element will be as tiny as possible */
+    width: 1px;
+    height: 1px;
+  }
+  #id2 {
+    font-size: 10px;
+    min-height: 1px;
+    max-height: 100px;
+
+    /* These values are extreme enough that they should be out of bounds for any implementation */
+    min-width: 10px;
+    max-width: 1000px;
+
+    /* This element will be as large as possible */
+    width: 1000px;
+    height: 1000px;
+  }
+  #id3 {
+    font-size: 10px;
+    width: auto;
+    height: auto;
+
+    /* There is a slight misalignment of the text (by 1px) when using
+       padding vs using width/height. Since this test's purpose is to
+       check that the bounds are identical, the color and background-color
+       are set to the same value to cover the slight text misalignment */
+    color:black;
+    background-color: black;
+
+    /* Only padding-top and padding-left are taken into account */
+    padding-top: 1000px;
+    padding-left: 1000px;
+    padding-bottom: 1px;
+    padding-right: 1px;
+  }
+</style>
+
+<div><permission id="id1" type="geolocation"></div>
+<div><permission id="id2" type="camera"></div>
+<div><permission id="id3" type="microphone"></div>
+</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes.tentative.html b/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes.tentative.html
new file mode 100644
index 0000000000..2010cd0a54
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/bounded-sizes.tentative.html
@@ -0,0 +1,75 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<link rel="help" href="https://github.com/WICG/PEPC/blob/main/explainer.md#locking-the-pepc-style">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<!--The permission element should have some limits for the min/max-width/height:
+  * min-width should be sufficient to fit the element text (depends on user agent implementation)
+  * max-width should be at most 3x min-width
+  * min-height should be sufficient to fit the element text (1em)
+  * max-height should be at most 3x min-height
+-->
+<style>
+  #id1 {
+    font-size: 10px;
+    width: auto;
+    height: auto;
+
+    min-height: 1px;
+    max-height: 100px;
+
+    padding-top: 12px;
+    padding-left: 60px;
+    padding-bottom: 1000px;
+    padding-right: 1000px;
+
+    /* These values are extreme enough that they should be out of bounds for any implementation */
+    min-width: 10px;
+    max-width: 1000px;
+  }
+  #id2 {
+    font-size: 10px;
+    width: auto;
+    height: auto;
+
+    min-height: 11px;
+    max-height: 29px;
+
+    padding-top: 5px;
+    padding-left: 45px;
+    padding-bottom: 6px;
+    padding-right: 46px;
+  }
+</style>
+
+
+<permission id="id1" type="geolocation">
+<permission id="id2" type="camera">
+
+<script>
+  test(function(){
+    let el_outside_bounds = document.getElementById("id1");
+    let min_height = getComputedStyle(el_outside_bounds).minHeight;
+    let max_height = getComputedStyle(el_outside_bounds).maxHeight;
+    assert_true(min_height === "calc(10px)" || min_height === "10px", "min-height");
+    assert_true(max_height === "calc(30px)" || max_height === "30px", "max-height");
+    assert_not_equals(getComputedStyle(el_outside_bounds).minWidth, "10px", "min-width");
+    assert_not_equals(getComputedStyle(el_outside_bounds).maxWidth, "1000px", "max-width");
+    assert_equals(getComputedStyle(el_outside_bounds).paddingLeft, "50px", "padding-left");
+    assert_equals(getComputedStyle(el_outside_bounds).paddingRight, "50px", "padding-right");
+    assert_equals(getComputedStyle(el_outside_bounds).paddingTop, "10px", "padding-top");
+    assert_equals(getComputedStyle(el_outside_bounds).paddingBottom, "10px", "padding-bottom");
+  }, "Properties with out-of-bounds values should be corrected");
+
+  test(function(){
+    let el_inside_bounds = document.getElementById("id2");
+    assert_equals(getComputedStyle(el_inside_bounds).minHeight, "calc(11px)", "min-height");
+    assert_equals(getComputedStyle(el_inside_bounds).maxHeight, "calc(29px)", "max-height");
+    assert_equals(getComputedStyle(el_inside_bounds).paddingLeft, "45px", "padding-left");
+    assert_equals(getComputedStyle(el_inside_bounds).paddingRight, "45px", "padding-right");
+    assert_equals(getComputedStyle(el_inside_bounds).paddingTop, "5px", "padding-top");
+    assert_equals(getComputedStyle(el_inside_bounds).paddingBottom, "5px", "padding-bottom");
+  }, "Properties with values in bounds should not be modified");
+</script>
+</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference-expected.html b/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference-expected.html
deleted file mode 100644
index 6a04c94c03..0000000000
--- a/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference-expected.html
+++ /dev/null
@@ -1,16 +0,0 @@
-<!DOCTYPE html>
-<meta charset=utf-8>
-<body>
-  <div>
-    The permission element should either be display 'none' or 'inline-block'
-  </div>
-
-<style>
-  #id1 {
-    display: inline-block;
-  }
-</style>
-
-<permission id="id1" type="geolocation">
-<span>After element</span>
-</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference.tentative.html b/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference.tentative.html
deleted file mode 100644
index 973a76d723..0000000000
--- a/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reference.tentative.html
+++ /dev/null
@@ -1,22 +0,0 @@
-<!DOCTYPE html>
-<meta charset=utf-8>
-<link rel="match" href="display-css-property-reference-expected.html">
-<link rel="help" href="https://github.com/WICG/PEPC/blob/main/explainer.md#locking-the-pepc-style">
-<body>
-  <div>
-    The permission element should either be display 'none' or 'inline-block'
-  </div>
-
-<style>
-  #id1 {
-    display: flex;
-  }
-  #id2 {
-    display: none;
-  }
-</style>
-
-<permission id="id1" type="geolocation">
-<permission id="id2" type="camera">
-<span>After element</span>
-</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest-ref.html b/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest-ref.html
new file mode 100644
index 0000000000..6a04c94c03
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest-ref.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<body>
+  <div>
+    The permission element should either be display 'none' or 'inline-block'
+  </div>
+
+<style>
+  #id1 {
+    display: inline-block;
+  }
+</style>
+
+<permission id="id1" type="geolocation">
+<span>After element</span>
+</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest.tentative.html b/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest.tentative.html
new file mode 100644
index 0000000000..e83786373d
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/permission-element/display-css-property-reftest.tentative.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<link rel="match" href="display-css-property-reftest-ref.html">
+<link rel="help" href="https://github.com/WICG/PEPC/blob/main/explainer.md#locking-the-pepc-style">
+<body>
+  <div>
+    The permission element should either be display 'none' or 'inline-block'
+  </div>
+
+<style>
+  #id1 {
+    display: flex;
+  }
+  #id2 {
+    display: none;
+  }
+</style>
+
+<permission id="id1" type="geolocation">
+<permission id="id2" type="camera">
+<span>After element</span>
+</body>
\ No newline at end of file
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-change-display.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-change-display.tentative.html
index 435929a6c1..4312a156ce 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-change-display.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-change-display.tentative.html
@@ -42,6 +42,7 @@ window.addEventListener('load', runTest);
     background: orange;
   }
   [popover] {
+    inset: auto;
     background: lime;
     padding:0;
     border:0;
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display-none.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display-none.tentative.html
index 55a11fafdb..8db022b126 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display-none.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display-none.tentative.html
@@ -15,6 +15,7 @@
     display: none;
   }
   [popover] {
+    inset: auto;
     background: lime;
     padding: 0;
     border: 0;
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display.tentative.html
index bddc44006d..a713540094 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-display.tentative.html
@@ -61,6 +61,7 @@ showDefaultopenPopoversOnLoad();
     background: orange;
   }
   [popover] {
+    inset: auto;
     background: lime;
     padding:0;
     border:0;
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-scroll-display.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-scroll-display.tentative.html
index 2c6b0bafb9..a301032a5b 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-scroll-display.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-scroll-display.tentative.html
@@ -40,6 +40,7 @@
     background: orange;
   }
   [popover] {
+    inset: auto;
     background: lime;
     padding:0;
     border:0;
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-transition.tentative.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-transition.tentative.tentative.html
index ae2a3a8e41..f6220f3c76 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-anchor-transition.tentative.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-anchor-transition.tentative.tentative.html
@@ -13,6 +13,7 @@ body {
 }
 
 #target {
+  inset: auto;
   transition: display 2s;
 }
 </style>
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-focus-2.html b/testing/web-platform/tests/html/semantics/popovers/popover-focus-2.html
index 892e5fd68f..8f24ace919 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-focus-2.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-focus-2.html
@@ -80,7 +80,7 @@ promise_test(async t => {
   assert_equals(document.activeElement,invoker2,'Focus should move within popover');
   await sendShiftTab();
   await sendShiftTab();
-  assert_equals(document.activeElement, button1 ,'Focus should not move back to invoker as it is non-focusable');
+  assert_equals(document.activeElement,invoker0,'Focus should not move back to invoker as it is non-focusable');
   // Reset invoker1 to focusable.
   invoker1.disabled = false;
   await verifyFocusOrder([button1, button2, invoker0, invoker1, inside_popover1, invoker2, inside_popover2, button3, button4],'set 1');
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-hover-crash-hang.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-hover-crash-hang.tentative.html
new file mode 100644
index 0000000000..60309398db
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-hover-crash-hang.tentative.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<meta charset="utf-8" />
+<title>Crash/hang test for popover hover behavior</title>
+<link rel="author" href="mailto:masonf@chromium.org">
+<link rel=help href="https://open-ui.org/components/popover-hint.research.explainer/">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/popover-utils.js"></script>
+
+<div id=menu popover=manual>
+  Popover
+  <button popovertarget="submenu"><span id=button>Button</span>
+    <div id=submenu popover=manual>Button-contained popover</div>
+  </button>
+</div>
+<button id=unrelated>Unrelated</button>
+
+<script>
+   promise_test(async (t) => {
+    menu.showPopover();
+    assert_true(menu.matches(':popover-open'));
+    await mouseHover(button,100);
+    button.click();
+    assert_true(menu.matches(':popover-open'));
+    assert_true(submenu.matches(':popover-open'));
+    await mouseHover(submenu,100);
+    await mouseHover(unrelated,100);
+    assert_true(submenu.matches(':popover-open'));
+    // This test passes if nothing crashes/hangs.
+   },'crash test');
+</script>
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss-scroll-within.html b/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss-scroll-within.html
new file mode 100644
index 0000000000..2329aea201
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss-scroll-within.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<meta charset="utf-8" />
+<title>Popover light dismiss behavior when scrolled within</title>
+<meta name="timeout" content="long">
+<link rel="author" href="mailto:masonf@chromium.org">
+<link rel=help href="https://open-ui.org/components/popover.research.explainer">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
+<script src="resources/popover-utils.js"></script>
+
+<style>
+  [popover] {
+    /* Position most popovers at the bottom-right, out of the way */
+    inset:auto;
+    bottom:0;
+    right:0;
+  }
+  [popover]::backdrop {
+    /* This should *not* affect anything: */
+    pointer-events: auto;
+  }
+</style>
+
+<div popover id=p>Inside popover
+  <div style="height:2000px;background:lightgreen"></div>
+  Bottom of popover6
+</div>
+<button popovertarget=p>Popover</button>
+<style>
+  #p6 {
+    width: 300px;
+    height: 300px;
+    overflow-y: scroll;
+  }
+</style>
+<script>
+  const popover = document.querySelector('#p');
+  promise_test(async () => {
+    popover.showPopover();
+    assert_equals(popover.scrollTop,0,'popover should start non-scrolled');
+    await new test_driver.Actions()
+       .scroll(0, 0, 0, 50, {origin: popover})
+       .send();
+    await waitForRender();
+    assert_true(popover.matches(':popover-open'),'popover should stay open');
+    assert_equals(popover.scrollTop,50,'popover should be scrolled');
+    popover.hidePopover();
+  },'Scrolling within a popover should not close the popover');
+</script>
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss.html b/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss.html
index 45db242e91..78b8674513 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-light-dismiss.html
@@ -303,33 +303,6 @@
   },'An invoking element that was not used to invoke the popover is not part of the ancestor chain');
 </script>
 
-<div popover id=p6>Inside popover 6
-  <div style="height:2000px;background:lightgreen"></div>
-  Bottom of popover6
-</div>
-<button popovertarget=p6>Popover 6</button>
-<style>
-  #p6 {
-    width: 300px;
-    height: 300px;
-    overflow-y: scroll;
-  }
-</style>
-<script>
-  const popover6 = document.querySelector('#p6');
-  promise_test(async () => {
-    popover6.showPopover();
-    assert_equals(popover6.scrollTop,0,'popover6 should start non-scrolled');
-    await new test_driver.Actions()
-       .scroll(0, 0, 0, 50, {origin: popover6})
-       .send();
-    await waitForRender();
-    assert_true(popover6.matches(':popover-open'),'popover6 should stay open');
-    assert_equals(popover6.scrollTop,50,'popover6 should be scrolled');
-    popover6.hidePopover();
-  },'Scrolling within a popover should not close the popover');
-</script>
-
 <my-element id="myElement">
   <template shadowrootmode="open">
     <button id=b7 popovertarget=p7 popovertargetaction=show tabindex="0">Popover7</button>
@@ -602,18 +575,26 @@ promise_test(async () => {
   p29.showPopover();
   assert_true(p29.matches(':popover-open'),'showing');
   let actions = new test_driver.Actions();
-  await actions.pointerMove(0,0,{origin: b29})
+  // Using the iframe's contentDocument as the origin would throw an error, so
+  // we are using iframe29 as the origin instead.
+  const iframe_box = iframe29.getBoundingClientRect();
+
+  await actions
+      .pointerMove(1,1,{origin: b29})
       .pointerDown({button: actions.ButtonType.LEFT})
+      .pointerMove(iframe_box.width / 2, iframe_box.height / 2, {origin: iframe29})
+      .pointerUp({button: actions.ButtonType.LEFT})
       .send();
-  await waitForRender();
-  assert_true(p29.matches(':popover-open'),'showing after pointerdown');
+  assert_true(p29.matches(':popover-open'), 'popover should be open after pointerUp in iframe.');
 
   actions = new test_driver.Actions();
-  await actions.pointerMove(0,0,{origin: iframe29.contentDocument.body})
+  await actions
+      .pointerMove(iframe_box.width / 2, iframe_box.height / 2, {origin: iframe29})
+      .pointerDown({button: actions.ButtonType.LEFT})
+      .pointerMove(1,1,{origin: b29})
       .pointerUp({button: actions.ButtonType.LEFT})
       .send();
-  await waitForRender();
-  assert_true(p29.matches(':popover-open'),'showing after pointerup');
+  assert_true(p29.matches(':popover-open'), 'popover should be open after pointerUp on main frame button.');
 },`Pointer down in one document and pointer up in another document shouldn't dismiss popover`);
 </script>
 
@@ -626,13 +607,10 @@ promise_test(async () => {
   p30.showPopover();
   assert_true(p30.matches(':popover-open'),'showing');
   let actions = new test_driver.Actions();
-  await actions.pointerMove(0,0,{origin: b30})
+  await actions
+      .pointerMove(2,2,{origin: b30})
       .pointerDown({button: actions.ButtonType.LEFT})
-      .send();
-  await waitForRender();
-  assert_true(p30.matches(':popover-open'),'showing after pointerdown');
-  actions = new test_driver.Actions();
-  await actions.pointerMove(0,0,{origin: b30b})
+      .pointerMove(2,2,{origin: b30b})
       .pointerUp({button: actions.ButtonType.LEFT})
       .send();
   await waitForRender();
diff --git a/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/basic.any.js b/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/basic.any.js
index 82cb3b215d..4876e82b0d 100644
--- a/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/basic.any.js
+++ b/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/basic.any.js
@@ -25,8 +25,8 @@ promise_test(async t => {
   // Use Date.now() to ensure that the module is not in the module map
   const specifier = "./empty-module.js?" + Date.now();
 
-  const getCount = ticker(1e7);
+  const getCount = ticker(1e6);
   await import(specifier);
-  assert_equals(getCount(), 1e7);
+  assert_equals(getCount(), 1e6);
 }, "import() should drain the microtask queue when fetching a new module");
 
diff --git a/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/inline-async-inserted-execorder.html b/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/inline-async-inserted-execorder.html
new file mode 100644
index 0000000000..0f51fd318b
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/scripting-1/the-script-element/module/inline-async-inserted-execorder.html
@@ -0,0 +1,70 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Inline async="" module scripts execute or throw parse errors asynchronously</title>
+<link rel="help" href="https://github.com/whatwg/html/issues/9864">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<body>
+<script>
+"use strict";
+setup({ allow_uncaught_exception: true });
+
+promise_test(async t => {
+  window.log = ["before any script execution"];
+
+  window.addEventListener("error", ev => {
+    window.log.push("error event on Window");
+  });
+
+  const noErrorScript = document.createElement("script");
+  noErrorScript.type = "module";
+  noErrorScript.async = true;
+  noErrorScript.textContent = "window.log.push('no error script executed');";
+
+  // This should queue a task to run the script, but not run it immediately.
+  document.head.append(noErrorScript);
+
+  log.push("after inserting noErrorScript");
+  assert_array_equals(window.log, [
+    "before any script execution",
+    "after inserting noErrorScript"
+  ]);
+
+  const parseErrorScript = document.createElement("script");
+  parseErrorScript.type = "module";
+  parseErrorScript.async = true;
+  parseErrorScript.textContent = "+++++";
+
+  // This should queue a task to fire the error event, but not fire it immediately.
+  document.head.append(parseErrorScript);
+
+  log.push("after inserting parseErrorScript");
+  assert_array_equals(window.log, [
+    "before any script execution",
+    "after inserting noErrorScript",
+    "after inserting parseErrorScript"
+  ]);
+
+  // After a microtask, the script run / error event must not happen.
+  queueMicrotask(t.step_func(() => {
+    assert_array_equals(window.log, [
+      "before any script execution",
+      "after inserting noErrorScript",
+      "after inserting parseErrorScript"
+    ]);
+  }));
+
+  // But it must eventually happen, after a full task.
+  await t.step_wait(() => window.log.length == 5, "5 items must eventually be logged");
+
+  // And when it does the order must be correct.
+  assert_array_equals(window.log, [
+    "before any script execution",
+    "after inserting noErrorScript",
+    "after inserting parseErrorScript",
+    "no error script executed",
+    "error event on Window"
+  ]);
+});
+</script>
diff --git a/testing/web-platform/tests/html/semantics/scripting-1/the-template-element/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/scripting-1/the-template-element/WEB_FEATURES.yml
new file mode 100644
index 0000000000..bd821885c7
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/scripting-1/the-template-element/WEB_FEATURES.yml
@@ -0,0 +1,3 @@
+features:
+- name: template
+  files: "**"
diff --git a/testing/web-platform/tests/html/semantics/selectors/pseudo-classes/WEB_FEATURES.yml b/testing/web-platform/tests/html/semantics/selectors/pseudo-classes/WEB_FEATURES.yml
new file mode 100644
index 0000000000..055a5fb4a3
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/selectors/pseudo-classes/WEB_FEATURES.yml
@@ -0,0 +1,11 @@
+features:
+- name: autofill
+  files:
+  - autofill.html
+- name: default
+  files:
+  - default.html
+- name: read-write-pseudos
+  files:
+  - readwrite-readonly-type-change.html
+  - readwrite-readonly.html
-- 
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