diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements-expected.txt
new file mode 100644
index 000000000000..2705f4eca4a1
--- /dev/null
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements-expected.txt
@@ -0,0 +1,186 @@
+
+PASS A <a popover> element should behave as a popover.
+PASS A <a> element should *not* behave as a popover.
+PASS A <abbr popover> element should behave as a popover.
+PASS A <abbr> element should *not* behave as a popover.
+PASS A <address popover> element should behave as a popover.
+PASS A <address> element should *not* behave as a popover.
+FAIL A <area popover> element should behave as a popover. assert_equals: After showPopover(), a popover should be visible: Expected this element to be visible expected true but got false
+FAIL A <area> element should *not* behave as a popover. assert_equals: A non-popover should start out visible: Expected this element to be visible expected true but got false
+PASS A <article popover> element should behave as a popover.
+PASS A <article> element should *not* behave as a popover.
+PASS A <aside popover> element should behave as a popover.
+PASS A <aside> element should *not* behave as a popover.
+PASS A <b popover> element should behave as a popover.
+PASS A <b> element should *not* behave as a popover.
+PASS A <bdi popover> element should behave as a popover.
+PASS A <bdi> element should *not* behave as a popover.
+PASS A <bdo popover> element should behave as a popover.
+PASS A <bdo> element should *not* behave as a popover.
+PASS A <blockquote popover> element should behave as a popover.
+PASS A <blockquote> element should *not* behave as a popover.
+PASS A <body popover> element should behave as a popover.
+PASS A <body> element should *not* behave as a popover.
+PASS A <button popover> element should behave as a popover.
+PASS A <button> element should *not* behave as a popover.
+PASS A <canvas popover> element should behave as a popover.
+PASS A <canvas> element should *not* behave as a popover.
+PASS A <caption popover> element should behave as a popover.
+PASS A <caption> element should *not* behave as a popover.
+PASS A <cite popover> element should behave as a popover.
+PASS A <cite> element should *not* behave as a popover.
+PASS A <code popover> element should behave as a popover.
+PASS A <code> element should *not* behave as a popover.
+PASS A <col popover> element should behave as a popover.
+PASS A <col> element should *not* behave as a popover.
+PASS A <colgroup popover> element should behave as a popover.
+PASS A <colgroup> element should *not* behave as a popover.
+PASS A <data popover> element should behave as a popover.
+PASS A <data> element should *not* behave as a popover.
+PASS A <dd popover> element should behave as a popover.
+PASS A <dd> element should *not* behave as a popover.
+PASS A <del popover> element should behave as a popover.
+PASS A <del> element should *not* behave as a popover.
+PASS A <details popover> element should behave as a popover.
+PASS A <details> element should *not* behave as a popover.
+PASS A <dfn popover> element should behave as a popover.
+PASS A <dfn> element should *not* behave as a popover.
+PASS A <div popover> element should behave as a popover.
+PASS A <div> element should *not* behave as a popover.
+PASS A <dl popover> element should behave as a popover.
+PASS A <dl> element should *not* behave as a popover.
+PASS A <dt popover> element should behave as a popover.
+PASS A <dt> element should *not* behave as a popover.
+PASS A <em popover> element should behave as a popover.
+PASS A <em> element should *not* behave as a popover.
+PASS A <fieldset popover> element should behave as a popover.
+PASS A <fieldset> element should *not* behave as a popover.
+PASS A <figcaption popover> element should behave as a popover.
+PASS A <figcaption> element should *not* behave as a popover.
+PASS A <figure popover> element should behave as a popover.
+PASS A <figure> element should *not* behave as a popover.
+PASS A <footer popover> element should behave as a popover.
+PASS A <footer> element should *not* behave as a popover.
+PASS A <form popover> element should behave as a popover.
+PASS A <form> element should *not* behave as a popover.
+PASS A <h1 popover> element should behave as a popover.
+PASS A <h1> element should *not* behave as a popover.
+PASS A <h2 popover> element should behave as a popover.
+PASS A <h2> element should *not* behave as a popover.
+PASS A <h3 popover> element should behave as a popover.
+PASS A <h3> element should *not* behave as a popover.
+PASS A <h4 popover> element should behave as a popover.
+PASS A <h4> element should *not* behave as a popover.
+PASS A <h5 popover> element should behave as a popover.
+PASS A <h5> element should *not* behave as a popover.
+PASS A <h6 popover> element should behave as a popover.
+PASS A <h6> element should *not* behave as a popover.
+PASS A <header popover> element should behave as a popover.
+PASS A <header> element should *not* behave as a popover.
+PASS A <hr popover> element should behave as a popover.
+PASS A <hr> element should *not* behave as a popover.
+PASS A <html popover> element should behave as a popover.
+PASS A <html> element should *not* behave as a popover.
+PASS A <i popover> element should behave as a popover.
+PASS A <i> element should *not* behave as a popover.
+PASS A <iframe popover> element should behave as a popover.
+PASS A <iframe> element should *not* behave as a popover.
+PASS A <img popover> element should behave as a popover.
+PASS A <img> element should *not* behave as a popover.
+PASS A <input popover> element should behave as a popover.
+PASS A <input> element should *not* behave as a popover.
+PASS A <ins popover> element should behave as a popover.
+PASS A <ins> element should *not* behave as a popover.
+PASS A <kbd popover> element should behave as a popover.
+PASS A <kbd> element should *not* behave as a popover.
+PASS A <label popover> element should behave as a popover.
+PASS A <label> element should *not* behave as a popover.
+PASS A <legend popover> element should behave as a popover.
+PASS A <legend> element should *not* behave as a popover.
+PASS A <li popover> element should behave as a popover.
+PASS A <li> element should *not* behave as a popover.
+PASS A <main popover> element should behave as a popover.
+PASS A <main> element should *not* behave as a popover.
+PASS A <map popover> element should behave as a popover.
+PASS A <map> element should *not* behave as a popover.
+PASS A <mark popover> element should behave as a popover.
+PASS A <mark> element should *not* behave as a popover.
+PASS A <menu popover> element should behave as a popover.
+PASS A <menu> element should *not* behave as a popover.
+PASS A <meter popover> element should behave as a popover.
+PASS A <meter> element should *not* behave as a popover.
+PASS A <nav popover> element should behave as a popover.
+PASS A <nav> element should *not* behave as a popover.
+PASS A <object popover> element should behave as a popover.
+PASS A <object> element should *not* behave as a popover.
+PASS A <ol popover> element should behave as a popover.
+PASS A <ol> element should *not* behave as a popover.
+FAIL A <optgroup popover> element should behave as a popover. assert_equals: After showPopover(), a popover should be visible: Expected this element to be visible expected true but got false
+FAIL A <optgroup> element should *not* behave as a popover. assert_equals: A non-popover should start out visible: Expected this element to be visible expected true but got false
+FAIL A <option popover> element should behave as a popover. assert_equals: After showPopover(), a popover should be visible: Expected this element to be visible expected true but got false
+FAIL A <option> element should *not* behave as a popover. assert_equals: A non-popover should start out visible: Expected this element to be visible expected true but got false
+PASS A <output popover> element should behave as a popover.
+PASS A <output> element should *not* behave as a popover.
+PASS A <p popover> element should behave as a popover.
+PASS A <p> element should *not* behave as a popover.
+PASS A <pre popover> element should behave as a popover.
+PASS A <pre> element should *not* behave as a popover.
+PASS A <progress popover> element should behave as a popover.
+PASS A <progress> element should *not* behave as a popover.
+PASS A <q popover> element should behave as a popover.
+PASS A <q> element should *not* behave as a popover.
+PASS A <rt popover> element should behave as a popover.
+PASS A <rt> element should *not* behave as a popover.
+PASS A <ruby popover> element should behave as a popover.
+PASS A <ruby> element should *not* behave as a popover.
+PASS A <s popover> element should behave as a popover.
+PASS A <s> element should *not* behave as a popover.
+PASS A <samp popover> element should behave as a popover.
+PASS A <samp> element should *not* behave as a popover.
+PASS A <section popover> element should behave as a popover.
+PASS A <section> element should *not* behave as a popover.
+PASS A <select popover> element should behave as a popover.
+PASS A <select> element should *not* behave as a popover.
+PASS A <small popover> element should behave as a popover.
+PASS A <small> element should *not* behave as a popover.
+PASS A <source popover> element should behave as a popover.
+PASS A <source> element should *not* behave as a popover.
+PASS A <span popover> element should behave as a popover.
+PASS A <span> element should *not* behave as a popover.
+PASS A <strong popover> element should behave as a popover.
+PASS A <strong> element should *not* behave as a popover.
+PASS A <sub popover> element should behave as a popover.
+PASS A <sub> element should *not* behave as a popover.
+PASS A <sup popover> element should behave as a popover.
+PASS A <sup> element should *not* behave as a popover.
+PASS A <summary popover> element should behave as a popover.
+PASS A <summary> element should *not* behave as a popover.
+PASS A <table popover> element should behave as a popover.
+PASS A <table> element should *not* behave as a popover.
+PASS A <tbody popover> element should behave as a popover.
+PASS A <tbody> element should *not* behave as a popover.
+PASS A <td popover> element should behave as a popover.
+PASS A <td> element should *not* behave as a popover.
+PASS A <textarea popover> element should behave as a popover.
+PASS A <textarea> element should *not* behave as a popover.
+PASS A <tfoot popover> element should behave as a popover.
+PASS A <tfoot> element should *not* behave as a popover.
+PASS A <th popover> element should behave as a popover.
+PASS A <th> element should *not* behave as a popover.
+PASS A <thead popover> element should behave as a popover.
+PASS A <thead> element should *not* behave as a popover.
+PASS A <time popover> element should behave as a popover.
+PASS A <time> element should *not* behave as a popover.
+PASS A <tr popover> element should behave as a popover.
+PASS A <tr> element should *not* behave as a popover.
+PASS A <track popover> element should behave as a popover.
+PASS A <track> element should *not* behave as a popover.
+PASS A <u popover> element should behave as a popover.
+PASS A <u> element should *not* behave as a popover.
+PASS A <ul popover> element should behave as a popover.
+PASS A <ul> element should *not* behave as a popover.
+PASS A <var popover> element should behave as a popover.
+PASS A <var> element should *not* behave as a popover.
+PASS A <video popover> element should behave as a popover.
+PASS A <video> element should *not* behave as a popover.
+
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements.html b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements.html
new file mode 100644
index 000000000000..d620f767882c
--- /dev/null
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements.html
@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<link rel="author" href="mailto:masonf@chromium.org">
+<link rel=help href="https://open-ui.org/components/popup.research.explainer">
+<meta name="timeout" content="long">
+<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>
+<script src="../../resources/common.js"></script>
+
+<body>
+<script>
+setup({ explicit_done: true });
+window.onload = () => {
+  // Loop through all HTML5 elements that render a box by default:
+  let elementsThatDontRender = ['audio','base','br','datalist','dialog','embed','head','link','meta','noscript','param','rp','script','slot','style','template','title','wbr'];
+  const elements = HTML5_ELEMENTS.filter(el => !elementsThatDontRender.includes(el));
+  elements.forEach(tag => {
+    test((t) => {
+      const element = document.createElement(tag);
+      element.setAttribute('popover','auto');
+      document.body.appendChild(element);
+      t.add_cleanup(() => element.remove());
+      assertIsFunctionalPopover(element);
+    }, `A <${tag} popover> element should behave as a popover.`);
+    test((t) => {
+      const element = document.createElement(tag);
+      document.body.appendChild(element);
+      t.add_cleanup(() => element.remove());
+      assertNotAPopover(element);
+    }, `A <${tag}> element should *not* behave as a popover.`);
+  });
+
+  done();
+};
+</script>
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic-expected.txt
index 55f84791cfe8..9da2aebf0c9d 100644
--- a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic-expected.txt
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic-expected.txt
@@ -17,194 +17,10 @@ PASS The element <div popover="popover">Invalid popover value - defaults to popo
 PASS The element <div popover="invalid">Invalid popover value - defaults to popover=manual</div> should behave as a popover.
 PASS The element <div>Not a popover</div> should *not* behave as a popover.
 PASS The element <dialog open="">Dialog without popover attribute</dialog> should *not* behave as a popover.
-PASS A <a popover> element should behave as a popover.
-PASS A <a> element should *not* behave as a popover.
-PASS A <abbr popover> element should behave as a popover.
-PASS A <abbr> element should *not* behave as a popover.
-PASS A <address popover> element should behave as a popover.
-PASS A <address> element should *not* behave as a popover.
-FAIL A <area popover> element should behave as a popover. assert_equals: After showPopover(), a popover should be visible: Expected this element to be visible expected true but got false
-FAIL A <area> element should *not* behave as a popover. assert_equals: A non-popover should start out visible: Expected this element to be visible expected true but got false
-PASS A <article popover> element should behave as a popover.
-PASS A <article> element should *not* behave as a popover.
-PASS A <aside popover> element should behave as a popover.
-PASS A <aside> element should *not* behave as a popover.
-PASS A <b popover> element should behave as a popover.
-PASS A <b> element should *not* behave as a popover.
-PASS A <bdi popover> element should behave as a popover.
-PASS A <bdi> element should *not* behave as a popover.
-PASS A <bdo popover> element should behave as a popover.
-PASS A <bdo> element should *not* behave as a popover.
-PASS A <blockquote popover> element should behave as a popover.
-PASS A <blockquote> element should *not* behave as a popover.
-PASS A <body popover> element should behave as a popover.
-PASS A <body> element should *not* behave as a popover.
-PASS A <button popover> element should behave as a popover.
-PASS A <button> element should *not* behave as a popover.
-PASS A <canvas popover> element should behave as a popover.
-PASS A <canvas> element should *not* behave as a popover.
-PASS A <caption popover> element should behave as a popover.
-PASS A <caption> element should *not* behave as a popover.
-PASS A <cite popover> element should behave as a popover.
-PASS A <cite> element should *not* behave as a popover.
-PASS A <code popover> element should behave as a popover.
-PASS A <code> element should *not* behave as a popover.
-PASS A <col popover> element should behave as a popover.
-PASS A <col> element should *not* behave as a popover.
-PASS A <colgroup popover> element should behave as a popover.
-PASS A <colgroup> element should *not* behave as a popover.
-PASS A <data popover> element should behave as a popover.
-PASS A <data> element should *not* behave as a popover.
-PASS A <dd popover> element should behave as a popover.
-PASS A <dd> element should *not* behave as a popover.
-PASS A <del popover> element should behave as a popover.
-PASS A <del> element should *not* behave as a popover.
-PASS A <details popover> element should behave as a popover.
-PASS A <details> element should *not* behave as a popover.
-PASS A <dfn popover> element should behave as a popover.
-PASS A <dfn> element should *not* behave as a popover.
-PASS A <div popover> element should behave as a popover.
-PASS A <div> element should *not* behave as a popover.
-PASS A <dl popover> element should behave as a popover.
-PASS A <dl> element should *not* behave as a popover.
-PASS A <dt popover> element should behave as a popover.
-PASS A <dt> element should *not* behave as a popover.
-PASS A <em popover> element should behave as a popover.
-PASS A <em> element should *not* behave as a popover.
-PASS A <fieldset popover> element should behave as a popover.
-PASS A <fieldset> element should *not* behave as a popover.
-PASS A <figcaption popover> element should behave as a popover.
-PASS A <figcaption> element should *not* behave as a popover.
-PASS A <figure popover> element should behave as a popover.
-PASS A <figure> element should *not* behave as a popover.
-PASS A <footer popover> element should behave as a popover.
-PASS A <footer> element should *not* behave as a popover.
-PASS A <form popover> element should behave as a popover.
-PASS A <form> element should *not* behave as a popover.
-PASS A <h1 popover> element should behave as a popover.
-PASS A <h1> element should *not* behave as a popover.
-PASS A <h2 popover> element should behave as a popover.
-PASS A <h2> element should *not* behave as a popover.
-PASS A <h3 popover> element should behave as a popover.
-PASS A <h3> element should *not* behave as a popover.
-PASS A <h4 popover> element should behave as a popover.
-PASS A <h4> element should *not* behave as a popover.
-PASS A <h5 popover> element should behave as a popover.
-PASS A <h5> element should *not* behave as a popover.
-PASS A <h6 popover> element should behave as a popover.
-PASS A <h6> element should *not* behave as a popover.
-PASS A <header popover> element should behave as a popover.
-PASS A <header> element should *not* behave as a popover.
-PASS A <hr popover> element should behave as a popover.
-PASS A <hr> element should *not* behave as a popover.
-PASS A <html popover> element should behave as a popover.
-PASS A <html> element should *not* behave as a popover.
-PASS A <i popover> element should behave as a popover.
-PASS A <i> element should *not* behave as a popover.
-PASS A <iframe popover> element should behave as a popover.
-PASS A <iframe> element should *not* behave as a popover.
-PASS A <img popover> element should behave as a popover.
-PASS A <img> element should *not* behave as a popover.
-PASS A <input popover> element should behave as a popover.
-PASS A <input> element should *not* behave as a popover.
-PASS A <ins popover> element should behave as a popover.
-PASS A <ins> element should *not* behave as a popover.
-PASS A <kbd popover> element should behave as a popover.
-PASS A <kbd> element should *not* behave as a popover.
-PASS A <label popover> element should behave as a popover.
-PASS A <label> element should *not* behave as a popover.
-PASS A <legend popover> element should behave as a popover.
-PASS A <legend> element should *not* behave as a popover.
-PASS A <li popover> element should behave as a popover.
-PASS A <li> element should *not* behave as a popover.
-PASS A <main popover> element should behave as a popover.
-PASS A <main> element should *not* behave as a popover.
-PASS A <map popover> element should behave as a popover.
-PASS A <map> element should *not* behave as a popover.
-PASS A <mark popover> element should behave as a popover.
-PASS A <mark> element should *not* behave as a popover.
-PASS A <menu popover> element should behave as a popover.
-PASS A <menu> element should *not* behave as a popover.
-PASS A <meter popover> element should behave as a popover.
-PASS A <meter> element should *not* behave as a popover.
-PASS A <nav popover> element should behave as a popover.
-PASS A <nav> element should *not* behave as a popover.
-PASS A <object popover> element should behave as a popover.
-PASS A <object> element should *not* behave as a popover.
-PASS A <ol popover> element should behave as a popover.
-PASS A <ol> element should *not* behave as a popover.
-FAIL A <optgroup popover> element should behave as a popover. assert_equals: After showPopover(), a popover should be visible: Expected this element to be visible expected true but got false
-FAIL A <optgroup> element should *not* behave as a popover. assert_equals: A non-popover should start out visible: Expected this element to be visible expected true but got false
-FAIL A <option popover> element should behave as a popover. assert_equals: After showPopover(), a popover should be visible: Expected this element to be visible expected true but got false
-FAIL A <option> element should *not* behave as a popover. assert_equals: A non-popover should start out visible: Expected this element to be visible expected true but got false
-PASS A <output popover> element should behave as a popover.
-PASS A <output> element should *not* behave as a popover.
-PASS A <p popover> element should behave as a popover.
-PASS A <p> element should *not* behave as a popover.
-PASS A <pre popover> element should behave as a popover.
-PASS A <pre> element should *not* behave as a popover.
-PASS A <progress popover> element should behave as a popover.
-PASS A <progress> element should *not* behave as a popover.
-PASS A <q popover> element should behave as a popover.
-PASS A <q> element should *not* behave as a popover.
-PASS A <rt popover> element should behave as a popover.
-PASS A <rt> element should *not* behave as a popover.
-PASS A <ruby popover> element should behave as a popover.
-PASS A <ruby> element should *not* behave as a popover.
-PASS A <s popover> element should behave as a popover.
-PASS A <s> element should *not* behave as a popover.
-PASS A <samp popover> element should behave as a popover.
-PASS A <samp> element should *not* behave as a popover.
-PASS A <section popover> element should behave as a popover.
-PASS A <section> element should *not* behave as a popover.
-PASS A <select popover> element should behave as a popover.
-PASS A <select> element should *not* behave as a popover.
-PASS A <small popover> element should behave as a popover.
-PASS A <small> element should *not* behave as a popover.
-PASS A <source popover> element should behave as a popover.
-PASS A <source> element should *not* behave as a popover.
-PASS A <span popover> element should behave as a popover.
-PASS A <span> element should *not* behave as a popover.
-PASS A <strong popover> element should behave as a popover.
-PASS A <strong> element should *not* behave as a popover.
-PASS A <sub popover> element should behave as a popover.
-PASS A <sub> element should *not* behave as a popover.
-PASS A <sup popover> element should behave as a popover.
-PASS A <sup> element should *not* behave as a popover.
-PASS A <summary popover> element should behave as a popover.
-PASS A <summary> element should *not* behave as a popover.
-PASS A <table popover> element should behave as a popover.
-PASS A <table> element should *not* behave as a popover.
-PASS A <tbody popover> element should behave as a popover.
-PASS A <tbody> element should *not* behave as a popover.
-PASS A <td popover> element should behave as a popover.
-PASS A <td> element should *not* behave as a popover.
-PASS A <textarea popover> element should behave as a popover.
-PASS A <textarea> element should *not* behave as a popover.
-PASS A <tfoot popover> element should behave as a popover.
-PASS A <tfoot> element should *not* behave as a popover.
-PASS A <th popover> element should behave as a popover.
-PASS A <th> element should *not* behave as a popover.
-PASS A <thead popover> element should behave as a popover.
-PASS A <thead> element should *not* behave as a popover.
-PASS A <time popover> element should behave as a popover.
-PASS A <time> element should *not* behave as a popover.
-PASS A <tr popover> element should behave as a popover.
-PASS A <tr> element should *not* behave as a popover.
-PASS A <track popover> element should behave as a popover.
-PASS A <track> element should *not* behave as a popover.
-PASS A <u popover> element should behave as a popover.
-PASS A <u> element should *not* behave as a popover.
-PASS A <ul popover> element should behave as a popover.
-PASS A <ul> element should *not* behave as a popover.
-PASS A <var popover> element should behave as a popover.
-PASS A <var> element should *not* behave as a popover.
-PASS A <video popover> element should behave as a popover.
-PASS A <video> element should *not* behave as a popover.
 PASS IDL attribute reflection
 PASS Popover attribute value should be case insensitive
 PASS Changing attribute values for popover should work
-FAIL Changing attribute values should close open popovers assert_false: expected false got true
+PASS Changing attribute values should close open popovers
 PASS Removing a visible popover=auto element from the document should close the popover
 PASS A showing popover=auto does not match :modal
 PASS Removing a visible popover=manual element from the document should close the popover
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic.html b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic.html
index c80534af9d19..c5937cd3237e 100644
--- a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic.html
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic.html
@@ -9,7 +9,6 @@
 <script src="/resources/testdriver-actions.js"></script>
 <script src="/resources/testdriver-vendor.js"></script>
 <script src="resources/popover-utils.js"></script>
-<script src="../../resources/common.js"></script>
 
 <div id=popovers>
   <div popover id=boolean>Pop up</div>
@@ -53,59 +52,6 @@
 setup({ explicit_done: true });
 window.onload = () => {
   const outsideElement = document.getElementById('outside');
-  function assertPopoverVisibility(popover, isPopover, expectedVisibility, message) {
-    const isVisible = isElementVisible(popover);
-    assert_equals(isVisible, expectedVisibility,`${message}: Expected this element to be ${expectedVisibility ? "visible" : "not visible"}`);
-    // Check other things related to being visible or not:
-    if (isVisible) {
-      assert_not_equals(window.getComputedStyle(popover).display,'none');
-      assert_equals(popover.matches(':open'),isPopover,`${message}: Visible popovers should match :open`);
-      assert_false(popover.matches(':closed'),`${message}: Visible popovers and *all* non-popovers should *not* match :closed`);
-    } else {
-      assert_equals(window.getComputedStyle(popover).display,'none',`${message}: Non-showing popovers should have display:none`);
-      assert_false(popover.matches(':open'),`${message}: Non-showing popovers should *not* match :open`);
-      assert_true(popover.matches(':closed'),`${message}: Non-showing popovers should match :closed`);
-    }
-  }
-  function assertIsFunctionalPopover(popover) {
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'A popover should start out hidden');
-    popover.showPopover();
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After showPopover(), a popover should be visible');
-    assert_throws_dom("InvalidStateError",() => popover.showPopover(),'Calling showPopover on a showing popover should throw InvalidStateError');
-    popover.hidePopover();
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After hidePopover(), a popover should be hidden');
-    assert_throws_dom("InvalidStateError",() => popover.hidePopover(),'Calling hidePopover on a hidden popover should throw InvalidStateError');
-    popover.togglePopover();
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After togglePopover() on hidden popover, it should be visible');
-    popover.togglePopover();
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After togglePopover() on visible popover, it should be hidden');
-    popover.togglePopover(/*force=*/true);
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After togglePopover(true) on hidden popover, it should be visible');
-    popover.togglePopover(/*force=*/true);
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After togglePopover(true) on visible popover, it should be visible');
-    popover.togglePopover(/*force=*/false);
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After togglePopover(false) on visible popover, it should be hidden');
-    popover.togglePopover(/*force=*/false);
-    assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After togglePopover(false) on hidden popover, it should be hidden');
-    const parent = popover.parentElement;
-    popover.remove();
-    assert_throws_dom("InvalidStateError",() => popover.showPopover(),'Calling showPopover on a disconnected popover should throw InvalidStateError');
-    assert_throws_dom("InvalidStateError",() => popover.hidePopover(),'Calling hidePopover on a disconnected popover should throw InvalidStateError');
-    assert_throws_dom("InvalidStateError",() => popover.togglePopover(),'Calling hidePopover on a disconnected popover should throw InvalidStateError');
-    parent.appendChild(popover);
-  }
-  function assertNotAPopover(nonPopover) {
-    // If the non-popover element nonetheless has a 'popover' attribute, it should
-    // be invisible. Otherwise, it should be visible.
-    const expectVisible = !nonPopover.hasAttribute('popover');
-    assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'A non-popover should start out visible');
-    assert_throws_dom("NotSupportedError",() => nonPopover.showPopover(),'Calling showPopover on a non-popover should throw NotSupported');
-    assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'Calling showPopover on a non-popover should leave it visible');
-    assert_throws_dom("NotSupportedError",() => nonPopover.hidePopover(),'Calling hidePopover on a non-popover should throw NotSupported');
-    assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'Calling hidePopover on a non-popover should leave it visible');
-    assert_throws_dom("NotSupportedError",() => nonPopover.togglePopover(),'Calling togglePopover on a non-popover should throw NotSupported');
-    assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'Calling togglePopover on a non-popover should leave it visible');
-  }
 
   // Start with the provided examples:
   Array.from(document.getElementById('popovers').children).forEach(popover => {
@@ -119,25 +65,6 @@
     }, `The element ${nonPopover.outerHTML} should *not* behave as a popover.`);
   });
 
-  // Then loop through all HTML5 elements that render a box by default:
-  let elementsThatDontRender = ['audio','base','br','datalist','dialog','embed','head','link','meta','noscript','param','rp','script','slot','style','template','title','wbr'];
-  const elements = HTML5_ELEMENTS.filter(el => !elementsThatDontRender.includes(el));
-  elements.forEach(tag => {
-    test((t) => {
-      const element = document.createElement(tag);
-      element.setAttribute('popover','auto');
-      document.body.appendChild(element);
-      t.add_cleanup(() => element.remove());
-      assertIsFunctionalPopover(element);
-    }, `A <${tag} popover> element should behave as a popover.`);
-    test((t) => {
-      const element = document.createElement(tag);
-      document.body.appendChild(element);
-      t.add_cleanup(() => element.remove());
-      assertNotAPopover(element);
-    }, `A <${tag}> element should *not* behave as a popover.`);
-  });
-
   function createPopover(t) {
     const popover = document.createElement('div');
     document.body.appendChild(popover);
@@ -233,8 +160,8 @@
       assert_false(popover.matches(':open'));
       popover.showPopover();
       assert_true(popover.matches(':open'));
-      popover.setAttribute('popover','manual');
     }
+    popover.setAttribute('popover','manual');
     assert_false(popover.matches(':open'));
     popover.showPopover();
     assert_true(popover.matches(':open'));
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-types-with-hints.tentative-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-types-with-hints.tentative-expected.txt
new file mode 100644
index 000000000000..6834ec8101be
--- /dev/null
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-types-with-hints.tentative-expected.txt
@@ -0,0 +1,11 @@
+Hint Nested hint
+Hint
+
+FAIL manuals do not close popovers Can't find variable: auto
+FAIL autos close hints but not manuals Can't find variable: auto
+FAIL hint is not closed by pre-existing auto Can't find variable: popover1
+FAIL If a popover=hint is shown, it should hide any other open popover=hint pop-ups, including ancestral pop-ups. (You can't nest popover=hint) assert_false: expected false got true
+FAIL If a popover=auto is shown, it should hide any open popover=hint, including if the popover=hint is an ancestral pop-up of the popover=auto. (You can't nest a popover=auto inside a popover=hint) assert_false: expected false got true
+FAIL If you: a) show a popover=auto (call it D), then b) show a descendent popover=hint of D (call it T), then c) hide D, then T should be hidden. (A popover=hint can be nested inside a popover=auto) assert_false: expected false got true
+PASS If you: a) show a popover=auto (call it D), then b) show a non-descendent popover=hint of D (call it T), then c) hide D, then T should be left showing. (Non-nested popover=hint can stay open when unrelated popover=autos are hidden)
+
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-types-with-hints.tentative.html b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-types-with-hints.tentative.html
new file mode 100644
index 000000000000..39d24a0ad437
--- /dev/null
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-types-with-hints.tentative.html
@@ -0,0 +1,184 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<link rel="author" href="mailto:masonf@chromium.org">
+<link rel=help href="https://open-ui.org/components/popup.research.explainer">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<div>
+  <div popover>Popover</div>
+  <div popover=hint>Hint</div>
+  <div popover=manual>Async</div>
+  <div popover=manual>Async</div>
+  <script>
+  {
+    const auto = document.currentScript.parentElement.querySelector('[popover=""]');
+    const hint = document.currentScript.parentElement.querySelector('[popover=hint]');
+    const manual = document.currentScript.parentElement.querySelectorAll('[popover=manual]')[0];
+    const manual2 = document.currentScript.parentElement.querySelectorAll('[popover=manual]')[1];
+    function assert_state_1(autoOpen,hintOpen,manualOpen,manual2Open) {
+      assert_equals(auto.matches(':open'),autoOpen,'auto open state is incorrect');
+      assert_equals(hint.matches(':open'),hintOpen,'hint open state is incorrect');
+      assert_equals(manual.matches(':open'),manualOpen,'manual open state is incorrect');
+      assert_equals(manual2.matches(':open'),manual2Open,'manual2 open state is incorrect');
+    }
+    test(() => {
+      assert_state_1(false,false,false,false);
+      auto.showPopover();
+      assert_state_1(true,false,false,false);
+      hint.showPopover();
+      assert_state_1(true,true,false,false);
+      manual.showPopover();
+      assert_state_1(true,true,true,false);
+      manual2.showPopover();
+      assert_state_1(true,true,true,true);
+      hint.hidePopover();
+      assert_state_1(true,false,true,true);
+      auto.hidePopover();
+      assert_state_1(false,false,true,true);
+      auto.showPopover();
+      hint.showPopover();
+      assert_state_1(true,true,true,true);
+      auto.hidePopover(); // Non-nested tooltips can stay open when unrelated popovers are hidden.
+      assert_state_1(false,true,true,true);
+      hint.hidePopover();
+      manual.hidePopover();
+      assert_state_1(false,false,false,true);
+      manual2.hidePopover();
+      assert_state_1(false,false,false,false);
+    },'manuals do not close popovers');
+
+    test(() => {
+      assert_state_1(false,false,false,false);
+      hint.showPopover();
+      manual.showPopover();
+      manual2.showPopover();
+      assert_state_1(false,true,true,true);
+      auto.showPopover();
+      assert_state_1(true,false,true,true);
+      auto.hidePopover();
+      assert_state_1(false,false,true,true);
+      manual.hidePopover();
+      manual2.hidePopover();
+      assert_state_1(false,false,false,false);
+    },'autos close hints but not manuals');
+  }
+  </script>
+</div>
+
+<div>
+  <div popover>popover 1
+    <div popover>popover 2
+      <p id=anchorid>Anchor</p>
+      <div popover>popover 3</div>
+    </div>
+  </div>
+  <div popover=hint anchor=anchorid>Hint anchored to pop-up</div>
+  <script>
+  {
+    const popover1 = document.currentScript.parentElement.querySelectorAll('[popover=""]')[0];
+    const popover2 = document.currentScript.parentElement.querySelectorAll('[popover=""]')[1];
+    const popover3 = document.currentScript.parentElement.querySelectorAll('[popover=""]')[2];
+    const hint = document.currentScript.parentElement.querySelector('[popover=hint]');
+    function assert_state_2(popover1Open,popover2Open,popover3Open,hintOpen) {
+      assert_equals(popover1.matches(':open'),popover1Open,'popover1 open state is incorrect');
+      assert_equals(popover2.matches(':open'),popover2Open,'popover2 open state is incorrect');
+      assert_equals(popover3.matches(':open'),popover3Open,'popover3 open state is incorrect');
+      assert_equals(hint.matches(':open'),hintOpen,'hint open state is incorrect');
+    }
+    test(() => {
+      assert_state_2(false,false,false,false);
+      popover1.showPopover();
+      popover2.showPopover();
+      popover3.showPopover();
+      assert_state_2(true,true,true,false);
+      hint.showPopover(); // Because hint is nested in popover2, popover3 should be hidden
+      assert_state_2(true,true,false,true);
+      popover1.hidePopover(); // Should close the hint, which is anchored to popover2
+      assert_state_2(false,false,false,false);
+    },'hint is not closed by pre-existing auto');
+  }
+  </script>
+</div>
+
+<div>
+  <div popover=hint>Hint
+    <div popover=hint>Nested hint</div>
+  </div>
+  <script>
+  test(() => {
+    const hint1 = document.currentScript.parentElement.querySelectorAll('[popover=hint]')[0];
+    const hint2 = document.currentScript.parentElement.querySelectorAll('[popover=hint]')[1];
+    hint1.showPopover();
+    assert_true(hint1.matches(':open'));
+    assert_false(hint2.matches(':open'));
+    hint2.showPopover();
+    assert_false(hint1.matches(':open'));
+    assert_true(hint2.matches(':open'));
+    hint2.hidePopover();
+  },'If a popover=hint is shown, it should hide any other open popover=hint pop-ups, including ancestral pop-ups. (You can\'t nest popover=hint)');
+  </script>
+</div>
+
+<div>
+  <div popover="hint">Hint
+    <div popover>Nested auto (note - never visible, since inside display:none subtree)</div>
+  </div>
+  <script>
+  test(() => {
+    const hint = document.currentScript.parentElement.querySelector('[popover=hint]');
+    const auto = document.currentScript.parentElement.querySelector('[popover=""]');
+    hint.showPopover();
+    assert_true(hint.matches(':open'));
+    assert_false(auto.matches(':open'));
+    auto.showPopover();
+    assert_false(hint.matches(':open'));
+    assert_true(auto.matches(':open'));
+    auto.hidePopover();
+  },'If a popover=auto is shown, it should hide any open popover=hint, including if the popover=hint is an ancestral pop-up of the popover=auto. (You can\'t nest a popover=auto inside a popover=hint)');
+  </script>
+</div>
+
+<div>
+  <div popover>Auto
+    <div popover>Nested Auto</div>
+    <div popover=hint>Nested hint</div>
+  </div>
+  <script>
+  test(() => {
+    const auto = document.currentScript.parentElement.querySelectorAll('[popover=""]')[0];
+    const auto2 = document.currentScript.parentElement.querySelectorAll('[popover=""]')[1];
+    const hint = document.currentScript.parentElement.querySelector('[popover=hint]');
+    auto.showPopover();
+    auto2.showPopover();
+    assert_true(auto.matches(':open'));
+    assert_true(auto2.matches(':open'));
+    hint.showPopover(); // This should hide auto2, since it is nested in auto1.
+    assert_true(auto.matches(':open'));
+    assert_false(auto2.matches(':open'));
+    assert_true(hint.matches(':open'));
+    auto.hidePopover(); // Should hide both auto and hint.
+    assert_false(auto.matches(':open'));
+    assert_false(hint.matches(':open'));
+  },'If you: a) show a popover=auto (call it D), then b) show a descendent popover=hint of D (call it T), then c) hide D, then T should be hidden. (A popover=hint can be nested inside a popover=auto)');
+  </script>
+</div>
+
+<div>
+  <div popover>Auto</div>
+  <div popover=hint>Non-Nested hint</div>
+  <script>
+  test(() => {
+    const auto = document.currentScript.parentElement.querySelector('[popover=""]');
+    const hint = document.currentScript.parentElement.querySelector('[popover=hint]');
+    auto.showPopover();
+    hint.showPopover();
+    assert_true(auto.matches(':open'));
+    assert_true(hint.matches(':open'));
+    auto.hidePopover();
+    assert_false(auto.matches(':open'));
+    assert_true(hint.matches(':open'));
+    hint.hidePopover();
+  },'If you: a) show a popover=auto (call it D), then b) show a non-descendent popover=hint of D (call it T), then c) hide D, then T should be left showing. (Non-nested popover=hint can stay open when unrelated popover=autos are hidden)');
+  </script>
+</div>
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/resources/popover-utils.js b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/resources/popover-utils.js
index 404b893bf03c..9c6ba77549bd 100644
--- a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/resources/popover-utils.js
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/resources/popover-utils.js
@@ -114,3 +114,59 @@ function popoverHintSupported() {
   testElement.popover = 'hint';
   return testElement.popover === 'hint';
 }
+
+function assertPopoverVisibility(popover, isPopover, expectedVisibility, message) {
+  const isVisible = isElementVisible(popover);
+  assert_equals(isVisible, expectedVisibility,`${message}: Expected this element to be ${expectedVisibility ? "visible" : "not visible"}`);
+  // Check other things related to being visible or not:
+  if (isVisible) {
+    assert_not_equals(window.getComputedStyle(popover).display,'none');
+    assert_equals(popover.matches(':open'),isPopover,`${message}: Visible popovers should match :open`);
+    assert_false(popover.matches(':closed'),`${message}: Visible popovers and *all* non-popovers should *not* match :closed`);
+  } else {
+    assert_equals(window.getComputedStyle(popover).display,'none',`${message}: Non-showing popovers should have display:none`);
+    assert_false(popover.matches(':open'),`${message}: Non-showing popovers should *not* match :open`);
+    assert_true(popover.matches(':closed'),`${message}: Non-showing popovers should match :closed`);
+  }
+}
+
+function assertIsFunctionalPopover(popover) {
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'A popover should start out hidden');
+  popover.showPopover();
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After showPopover(), a popover should be visible');
+  assert_throws_dom("InvalidStateError",() => popover.showPopover(),'Calling showPopover on a showing popover should throw InvalidStateError');
+  popover.hidePopover();
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After hidePopover(), a popover should be hidden');
+  assert_throws_dom("InvalidStateError",() => popover.hidePopover(),'Calling hidePopover on a hidden popover should throw InvalidStateError');
+  popover.togglePopover();
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After togglePopover() on hidden popover, it should be visible');
+  popover.togglePopover();
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After togglePopover() on visible popover, it should be hidden');
+  popover.togglePopover(/*force=*/true);
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After togglePopover(true) on hidden popover, it should be visible');
+  popover.togglePopover(/*force=*/true);
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/true, 'After togglePopover(true) on visible popover, it should be visible');
+  popover.togglePopover(/*force=*/false);
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After togglePopover(false) on visible popover, it should be hidden');
+  popover.togglePopover(/*force=*/false);
+  assertPopoverVisibility(popover, /*isPopover*/true, /*expectedVisibility*/false, 'After togglePopover(false) on hidden popover, it should be hidden');
+  const parent = popover.parentElement;
+  popover.remove();
+  assert_throws_dom("InvalidStateError",() => popover.showPopover(),'Calling showPopover on a disconnected popover should throw InvalidStateError');
+  assert_throws_dom("InvalidStateError",() => popover.hidePopover(),'Calling hidePopover on a disconnected popover should throw InvalidStateError');
+  assert_throws_dom("InvalidStateError",() => popover.togglePopover(),'Calling hidePopover on a disconnected popover should throw InvalidStateError');
+  parent.appendChild(popover);
+}
+
+function assertNotAPopover(nonPopover) {
+  // If the non-popover element nonetheless has a 'popover' attribute, it should
+  // be invisible. Otherwise, it should be visible.
+  const expectVisible = !nonPopover.hasAttribute('popover');
+  assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'A non-popover should start out visible');
+  assert_throws_dom("NotSupportedError",() => nonPopover.showPopover(),'Calling showPopover on a non-popover should throw NotSupported');
+  assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'Calling showPopover on a non-popover should leave it visible');
+  assert_throws_dom("NotSupportedError",() => nonPopover.hidePopover(),'Calling hidePopover on a non-popover should throw NotSupported');
+  assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'Calling hidePopover on a non-popover should leave it visible');
+  assert_throws_dom("NotSupportedError",() => nonPopover.togglePopover(),'Calling togglePopover on a non-popover should throw NotSupported');
+  assertPopoverVisibility(nonPopover, /*isPopover*/false, expectVisible, 'Calling togglePopover on a non-popover should leave it visible');
+}
diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/w3c-import.log
index c38631c7aab8..f2847864eb77 100644
--- a/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/w3c-import.log
+++ b/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/w3c-import.log
@@ -35,6 +35,7 @@ List of files:
 /LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-appearance-expected.html
 /LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-appearance-ref.html
 /LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-appearance.html
+/LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements.html
 /LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic.html
 /LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-backdrop-appearance-expected.html
 /LayoutTests/imported/w3c/web-platform-tests/html/semantics/popovers/popover-backdrop-appearance-ref.html
diff --git a/LayoutTests/tests-options.json b/LayoutTests/tests-options.json
index 6d393a673265..9f657efe3e7f 100644
--- a/LayoutTests/tests-options.json
+++ b/LayoutTests/tests-options.json
@@ -4025,6 +4025,9 @@
     "imported/w3c/web-platform-tests/html/semantics/links/links-created-by-a-and-area-elements/target_blank_implicit_noopener_base.html": [
         "slow"
     ],
+    "imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-all-elements.html": [
+        "slow"
+    ],
     "imported/w3c/web-platform-tests/html/semantics/popovers/popover-attribute-basic.html": [
         "slow"
     ],
