diff --git a/testing/web-platform/tests/html/semantics/popups/popup-appearance-ref.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-appearance-ref.tentative.html
index 43e3fd4ab7ad9..57edb7c583bf8 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-appearance-ref.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-appearance-ref.tentative.html
@@ -5,16 +5,14 @@
 
 <style>
 .fake-pop-up {top: 100px; bottom: auto;}
-#blank {left: -400px;}
-#auto {left: -200px;}
-#hint {left: 0;}
-#manual {left: 200px;}
-#invalid {left: 400px;}
+#blank {left: -300px;}
+#auto {left: -100px;}
+#manual {left: 100px;}
+#invalid {left: 300px;}
 </style>
 
-<p>There should be five pop-ups with similar appearance.</p>
+<p>There should be four pop-ups with similar appearance.</p>
 <div class="fake-pop-up" id=blank>Blank</div>
 <div class="fake-pop-up" id=auto>Auto</div>
-<div class="fake-pop-up" id=hint>Hint</div>
 <div class="fake-pop-up" id=manual>Manual</div>
 <div class="fake-pop-up" id=invalid>Invalid</div>
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-appearance.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-appearance.tentative.html
index 942734e203e13..3a848336c5f3a 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-appearance.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-appearance.tentative.html
@@ -7,18 +7,16 @@
 
 <style>
 [popup] {top: 100px; bottom: auto;}
-[popup=""] {left: -400px}
-[popup=auto] {left: -200px; }
-[popup=hint] {left: 0; }
-[popup=manual] {left: 200px; }
-[popup=invalid] {left: 400px; }
+[popup=""] {left: -300px}
+[popup=auto] {left: -100px; }
+[popup=manual] {left: 100px; }
+[popup=invalid] {left: 300px; }
 </style>
 
-<p>There should be five pop-ups with similar appearance.</p>
+<p>There should be four pop-ups with similar appearance.</p>
 <div popup>Blank
   <div popup=auto>Auto</div>
 </div>
-<div popup=hint>Hint</div>
 <div popup=manual>Manual</div>
 <!-- This ensures unsupported popup values are treated as popup=manual -->
 <div popup=invalid>Invalid</div>
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-attribute-basic.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-attribute-basic.tentative.html
index c20499c3f30fd..de8d4d5f89700 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-attribute-basic.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-attribute-basic.tentative.html
@@ -11,7 +11,6 @@
   <div popup id=boolean>Pop up</div>
   <div popup="">Pop up</div>
   <div popup=auto>Pop up</div>
-  <div popup=hint>Pop up</div>
   <div popup=manual>Pop up</div>
   <article popup>Different element type</article>
   <header popup>Different element type</header>
@@ -116,20 +115,18 @@
     // Getting the `popUp` IDL value only retrieves valid values.
     const popUp = createPopUp(t);
     assert_equals(popUp.popUp,'auto');
-    popUp.setAttribute('popup','hint');
-    assert_equals(popUp.popUp,'hint');
-    popUp.setAttribute('popup','HiNt');
-    assert_equals(popUp.popUp,'hint','Case is normalized in IDL');
-    assert_equals(popUp.getAttribute('popup'),'HiNt','Case is *not* normalized/changed in the content attribute');
-    popUp.popUp='hInT';
-    assert_equals(popUp.popUp,'hint','Case is normalized in IDL');
-    assert_equals(popUp.getAttribute('popup'),'hInT','Value set from IDL is propagated exactly to the content attribute');
+    popUp.setAttribute('popup','auto');
+    assert_equals(popUp.popUp,'auto');
+    popUp.setAttribute('popup','AuTo');
+    assert_equals(popUp.popUp,'auto','Case is normalized in IDL');
+    assert_equals(popUp.getAttribute('popup'),'AuTo','Case is *not* normalized/changed in the content attribute');
+    popUp.popUp='aUtO';
+    assert_equals(popUp.popUp,'auto','Case is normalized in IDL');
+    assert_equals(popUp.getAttribute('popup'),'aUtO','Value set from IDL is propagated exactly to the content attribute');
     popUp.setAttribute('popup','invalid');
     assert_equals(popUp.popUp,'manual','Invalid values should reflect as "manual"');
     popUp.removeAttribute('popup');
     assert_equals(popUp.popUp,null,'No value should reflect as null');
-    popUp.popUp='hint';
-    assert_equals(popUp.getAttribute('popup'),'hint');
     popUp.popUp='auto';
     assert_equals(popUp.getAttribute('popup'),'auto');
     popUp.popUp='';
@@ -176,11 +173,11 @@
   test((t) => {
     const popUp = createPopUp(t);
     assertIsFunctionalPopUp(popUp);
-    popUp.setAttribute('popup','hint'); // Change pop-up type
+    popUp.setAttribute('popup','manual'); // Change pop-up type
     assertIsFunctionalPopUp(popUp);
     popUp.setAttribute('popup','invalid'); // Change pop-up type to something invalid
     assertIsFunctionalPopUp(popUp);
-    popUp.popUp = 'hint'; // Change pop-up type via IDL
+    popUp.popUp = 'manual'; // Change pop-up type via IDL
     assertIsFunctionalPopUp(popUp);
     popUp.popUp = 'invalid'; // Make invalid via IDL (treated as "manual")
     assertIsFunctionalPopUp(popUp);
@@ -190,11 +187,7 @@
     const popUp = createPopUp(t);
     popUp.showPopUp();
     assert_true(popUp.matches(':open'));
-    popUp.setAttribute('popup','hint'); // Change pop-up type
-    assert_false(popUp.matches(':open'));
-    popUp.showPopUp();
-    assert_true(popUp.matches(':open'));
-    popUp.setAttribute('popup','manual');
+    popUp.setAttribute('popup','manual'); // Change pop-up type
     assert_false(popUp.matches(':open'));
     popUp.showPopUp();
     assert_true(popUp.matches(':open'));
@@ -217,7 +210,8 @@
     }
   }
 
-  ["auto","hint","manual"].forEach(type => {
+  const validTypes = ["auto","manual"];
+  validTypes.forEach(type => {
     test((t) => {
       const popUp = createPopUp(t);
       popUp.setAttribute('popup',type);
@@ -241,7 +235,6 @@
     }
   });
 
-  const validTypes = ["auto","hint","manual"];
   function interpretedType(typeString,method) {
     if (validTypes.includes(typeString))
       return typeString;
@@ -308,8 +301,7 @@
                     popUp.hidePopUp();
                     break;
                   case 'auto':
-                  case 'hint':
-                    assert_false(popUp.matches(':open'),'A popup=auto/hint should light-dismiss');
+                    assert_false(popUp.matches(':open'),'A popup=auto should light-dismiss');
                     break;
                 }
               }
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance-ref.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance-ref.tentative.html
index 4cb0d99569944..34dc357ba208d 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance-ref.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance-ref.tentative.html
@@ -33,7 +33,7 @@
 <p>Test for [popup]::backdrop presence and stacking order. The test passes
   if there are 3 stacked boxes, with the brightest green on top.</p>
 <div popup id=bottom>Bottom
-  <div popup=hint id=middle>Middle
+  <div popup id=middle>Middle
     <div popup=manual id=top>Top</div>
   </div>
 </div>
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance.tentative.html
index a2f761fa8170d..1a4c6bac65f49 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-backdrop-appearance.tentative.html
@@ -35,7 +35,7 @@
 <p>Test for [popup]::backdrop presence and stacking order. The test passes
   if there are 3 stacked boxes, with the brightest green on top.</p>
 <div popup id=bottom>Bottom
-  <div popup=hint id=middle>Middle
+  <div popup id=middle>Middle
     <div popup=manual id=top>Top</div>
   </div>
 </div>
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-defaultopen-hints.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-defaultopen-hints.tentative.html
deleted file mode 100644
index a7535fab20342..0000000000000
--- a/testing/web-platform/tests/html/semantics/popups/popup-defaultopen-hints.tentative.html
+++ /dev/null
@@ -1,20 +0,0 @@
-<!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>
-<script src="resources/popup-utils.js"></script>
-
-<div popup=hint defaultopen>This is a popup=hint with defaultopen, which should NOT be open upon load</div>
-
-<script>
-  promise_test(async () => {
-    await waitForRender();
-    await waitForRender();
-    const popUp = document.querySelector('[popup]');
-    assert_false(popUp.matches(':open'),'defaultopen does not apply to hint pop-ups');
-    assert_true(popUp.hasAttribute('defaultopen'),'attribute should still be present');
-    assert_true(popUp.defaultOpen,'defaultopen should be present/true, even if not opened');
-  }, "The defaultopen attribute should not apply to popup=hint");
-</script>
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-invoking-attribute.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-invoking-attribute.tentative.html
index b281e1f4c06b1..63a3c7f443a34 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-invoking-attribute.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-invoking-attribute.tentative.html
@@ -67,7 +67,7 @@
   ...unsupportedTypes,
 ];
 window.addEventListener('load', () => {
-  ["auto","hint","manual"].forEach(type => {
+  ["auto","manual"].forEach(type => {
     invokers.forEach(testcase => {
       let t_set = [1], s_set = [1], h_set = [1];
       if (testcase.supported) {
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-light-dismiss.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-light-dismiss.tentative.html
index 8848806cab773..d012942c14aa5 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-light-dismiss.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-light-dismiss.tentative.html
@@ -458,53 +458,6 @@
 },'Ensure circular/convoluted ancestral relationships are functional, with a direct showPopUp()');
 </script>
 
-
-<div popup id=p10>Popup</div>
-<div popup=hint id=p11>Hint</div>
-<div popup=manual id=p12>Manual</div>
-<style>
-  #p10 {top:100px;}
-  #p11 {top:200px;}
-  #p12 {top:300px;}
-</style>
-<script>
-promise_test(async () => {
-  const auto = document.querySelector('#p10');
-  const hint = document.querySelector('#p11');
-  const manual = document.querySelector('#p12');
-  // All three can be open at once, if shown in this order:
-  auto.showPopUp();
-  hint.showPopUp();
-  manual.showPopUp();
-  assert_true(auto.matches(':open'));
-  assert_true(hint.matches(':open'));
-  assert_true(manual.matches(':open'));
-  // Clicking the hint will close the auto, but not the manual.
-  await clickOn(hint);
-  assert_false(auto.matches(':open'),'auto should be hidden');
-  assert_true(hint.matches(':open'),'hint should stay open');
-  assert_true(manual.matches(':open'),'manual does not light dismiss');
-  // Clicking outside should close the hint, but not the manual:
-  await clickOn(outside);
-  assert_false(auto.matches(':open'));
-  assert_false(hint.matches(':open'),'hint should close');
-  assert_true(manual.matches(':open'),'manual does not light dismiss');
-  manual.hidePopUp();
-  assert_false(manual.matches(':open'));
-  auto.showPopUp();
-  hint.showPopUp();
-  assert_true(auto.matches(':open'));
-  assert_true(hint.matches(':open'));
-  // Clicking on the auto should close the hint:
-  await clickOn(auto);
-  assert_true(auto.matches(':open'),'auto should stay open');
-  assert_false(hint.matches(':open'),'hint should light dismiss');
-  auto.hidePopUp();
-  assert_false(auto.matches(':open'));
-},'Light dismiss of mixed popup types');
-</script>
-
-
 <div popup id=p13>Pop-up 1
   <div popup id=p14>Pop-up 2
     <div popup id=p15>Pop-up 3</div>
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-manual-crash.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-manual-crash.tentative.html
index b3430a451333c..bbc01a47ad935 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-manual-crash.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-manual-crash.tentative.html
@@ -6,17 +6,15 @@
 
 <style>
 [popup] {top: 100px; bottom: auto;}
-[popup=""] {left: -300px}
-[popup=auto] {left: -100px; }
-[popup=hint] {left: 100px; }
-[popup=manual] {left: 300px; }
+[popup=""] {left: -200px}
+[popup=auto] {left: 0; }
+[popup=manual] {left: 200px; }
 </style>
 
 <p>This test passes if it does not crash.</p>
-<div popup>Blank
-  <div popup=auto>Auto</div>
+<div popup>Auto1
+  <div popup=auto>Auto2</div>
 </div>
-<div popup=hint>Hint</div>
 <div popup=manual>Manual</div>
 <script>
   document.querySelectorAll('[popup]').forEach(p => p.showPopUp());
diff --git a/testing/web-platform/tests/html/semantics/popups/popup-types.tentative.html b/testing/web-platform/tests/html/semantics/popups/popup-types.tentative.html
index f9479cbc8491c..d1802b09b4319 100644
--- a/testing/web-platform/tests/html/semantics/popups/popup-types.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popups/popup-types.tentative.html
@@ -7,178 +7,33 @@
 
 <div>
   <div popup>Popup</div>
-  <div popup=hint>Hint</div>
   <div popup=manual>Async</div>
   <div popup=manual>Async</div>
   <script>
   {
     const auto = document.currentScript.parentElement.querySelector('[popup=""]');
-    const hint = document.currentScript.parentElement.querySelector('[popup=hint]');
     const manual = document.currentScript.parentElement.querySelectorAll('[popup=manual]')[0];
     const manual2 = document.currentScript.parentElement.querySelectorAll('[popup=manual]')[1];
-    function assert_state_1(autoOpen,hintOpen,manualOpen,manual2Open) {
+    function assert_state_1(autoOpen,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);
+      assert_state_1(false,false,false);
       auto.showPopUp();
-      assert_state_1(true,false,false,false);
-      hint.showPopUp();
-      assert_state_1(true,true,false,false);
+      assert_state_1(true,false,false);
       manual.showPopUp();
-      assert_state_1(true,true,true,false);
+      assert_state_1(true,true,false);
       manual2.showPopUp();
-      assert_state_1(true,true,true,true);
-      hint.hidePopUp();
-      assert_state_1(true,false,true,true);
+      assert_state_1(true,true,true);
       auto.hidePopUp();
-      assert_state_1(false,false,true,true);
-      auto.showPopUp();
-      hint.showPopUp();
-      assert_state_1(true,true,true,true);
-      auto.hidePopUp(); // Non-nested tooltips can stay open when unrelated popups are hidden.
-      assert_state_1(false,true,true,true);
-      hint.hidePopUp();
-      manual.hidePopUp();
-      assert_state_1(false,false,false,true);
-      manual2.hidePopUp();
-      assert_state_1(false,false,false,false);
-    },'hints and manuals do not close pop-ups');
-
-    test(() => {
-      assert_state_1(false,false,false,false);
-      hint.showPopUp();
-      manual.showPopUp();
-      manual2.showPopUp();
-      assert_state_1(false,true,true,true);
-      auto.showPopUp();
-      assert_state_1(true,false,true,true);
-      auto.hidePopUp();
-      assert_state_1(false,false,true,true);
+      assert_state_1(false,true,true);
       manual.hidePopUp();
+      assert_state_1(false,false,true);
       manual2.hidePopUp();
-      assert_state_1(false,false,false,false);
-    },'autos close hints but not manuals');
-  }
-  </script>
-</div>
-
-<div>
-  <div popup>Popup 1
-    <div popup>Popup 2
-      <p id=anchorid>Anchor</p>
-      <div popup>Popup 3</div>
-    </div>
-  </div>
-  <div popup=hint anchor=anchorid>Hint anchored to pop-up</div>
-  <script>
-  {
-    const popUp1 = document.currentScript.parentElement.querySelectorAll('[popup=""]')[0];
-    const popUp2 = document.currentScript.parentElement.querySelectorAll('[popup=""]')[1];
-    const popUp3 = document.currentScript.parentElement.querySelectorAll('[popup=""]')[2];
-    const hint = document.currentScript.parentElement.querySelector('[popup=hint]');
-    function assert_state_2(popUp1Open,popUp2Open,popUp3Open,hintOpen) {
-      assert_equals(popUp1.matches(':open'),popUp1Open,'popUp1 open state is incorrect');
-      assert_equals(popUp2.matches(':open'),popUp2Open,'popup2 open state is incorrect');
-      assert_equals(popUp3.matches(':open'),popUp3Open,'popup3 open state is incorrect');
-      assert_equals(hint.matches(':open'),hintOpen,'hint open state is incorrect');
-    }
-    test(() => {
-      assert_state_2(false,false,false,false);
-      popUp1.showPopUp();
-      popUp2.showPopUp();
-      popUp3.showPopUp();
-      assert_state_2(true,true,true,false);
-      hint.showPopUp(); // Because hint is nested in popUp2, popUp3 should be hidden
-      assert_state_2(true,true,false,true);
-      popUp1.hidePopUp(); // Should close the hint, which is anchored to popUp2
-      assert_state_2(false,false,false,false);
-    },'hint is not closed by pre-existing auto');
+      assert_state_1(false,false,false);
+    },'manuals do not close pop-ups');
   }
   </script>
 </div>
-
-<div>
-  <div popup=hint>Hint
-    <div popup=hint>Nested hint</div>
-  </div>
-  <script>
-  test(() => {
-    const hint1 = document.currentScript.parentElement.querySelectorAll('[popup=hint]')[0];
-    const hint2 = document.currentScript.parentElement.querySelectorAll('[popup=hint]')[1];
-    hint1.showPopUp();
-    assert_true(hint1.matches(':open'));
-    assert_false(hint2.matches(':open'));
-    hint2.showPopUp();
-    assert_false(hint1.matches(':open'));
-    assert_true(hint2.matches(':open'));
-    hint2.hidePopUp();
-  },'If a popup=hint is shown, it should hide any other open popup=hint pop-ups, including ancestral pop-ups. (You can\'t nest popup=hint)');
-  </script>
-</div>
-
-<div>
-  <div popup="hint">Hint
-    <div popup>Nested auto (note - never visible, since inside display:none subtree)</div>
-  </div>
-  <script>
-  test(() => {
-    const hint = document.currentScript.parentElement.querySelector('[popup=hint]');
-    const auto = document.currentScript.parentElement.querySelector('[popup=""]');
-    hint.showPopUp();
-    assert_true(hint.matches(':open'));
-    assert_false(auto.matches(':open'));
-    auto.showPopUp();
-    assert_false(hint.matches(':open'));
-    assert_true(auto.matches(':open'));
-    auto.hidePopUp();
-  },'If a popup=auto is shown, it should hide any open popup=hint, including if the popup=hint is an ancestral pop-up of the popup=auto. (You can\'t nest a popup=auto inside a popup=hint)');
-  </script>
-</div>
-
-<div>
-  <div popup>Auto
-    <div popup>Nested Auto</div>
-    <div popup=hint>Nested hint</div>
-  </div>
-  <script>
-  test(() => {
-    const auto = document.currentScript.parentElement.querySelectorAll('[popup=""]')[0];
-    const auto2 = document.currentScript.parentElement.querySelectorAll('[popup=""]')[1];
-    const hint = document.currentScript.parentElement.querySelector('[popup=hint]');
-    auto.showPopUp();
-    auto2.showPopUp();
-    assert_true(auto.matches(':open'));
-    assert_true(auto2.matches(':open'));
-    hint.showPopUp(); // 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.hidePopUp(); // Should hide both auto and hint.
-    assert_false(auto.matches(':open'));
-    assert_false(hint.matches(':open'));
-  },'If you: a) show a popup=auto (call it D), then b) show a descendent popup=hint of D (call it T), then c) hide D, then T should be hidden. (A popup=hint can be nested inside a popup=auto)');
-  </script>
-</div>
-
-<div>
-  <div popup>Auto</div>
-  <div popup=hint>Non-Nested hint</div>
-  <script>
-  test(() => {
-    const auto = document.currentScript.parentElement.querySelector('[popup=""]');
-    const hint = document.currentScript.parentElement.querySelector('[popup=hint]');
-    auto.showPopUp();
-    hint.showPopUp();
-    assert_true(auto.matches(':open'));
-    assert_true(hint.matches(':open'));
-    auto.hidePopUp();
-    assert_false(auto.matches(':open'));
-    assert_true(hint.matches(':open'));
-    hint.hidePopUp();
-  },'If you: a) show a popup=auto (call it D), then b) show a non-descendent popup=hint of D (call it T), then c) hide D, then T should be left showing. (Non-nested popup=hint can stay open when unrelated popup=autos are hidden)');
-  </script>
-</div>