diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index c6171166249..392e55b4cdc 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -36036,6 +36036,18 @@
             "url": "/cssom-view/scrolling-no-browsing-context.html"
           }
         ],
+        "html/semantics/embedded-content/the-iframe-element/change_parentage.html": [
+          {
+            "path": "html/semantics/embedded-content/the-iframe-element/change_parentage.html",
+            "url": "/html/semantics/embedded-content/the-iframe-element/change_parentage.html"
+          }
+        ],
+        "html/semantics/embedded-content/the-iframe-element/same_origin_parentage.html": [
+          {
+            "path": "html/semantics/embedded-content/the-iframe-element/same_origin_parentage.html",
+            "url": "/html/semantics/embedded-content/the-iframe-element/same_origin_parentage.html"
+          }
+        ],
         "url/url-domainToUnicode.html": [
           {
             "path": "url/url-domainToUnicode.html",
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 4fa28bc7fe3..24af8aa6f41 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -6448,12 +6448,6 @@
             "url": "/_mozilla/mozilla/iframe-unblock-onload.html"
           }
         ],
-        "mozilla/iframe/same_origin_parentage.html": [
-          {
-            "path": "mozilla/iframe/same_origin_parentage.html",
-            "url": "/_mozilla/mozilla/iframe/same_origin_parentage.html"
-          }
-        ],
         "mozilla/iframe_contentDocument.html": [
           {
             "path": "mozilla/iframe_contentDocument.html",
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_child.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_child.html
new file mode 100644
index 00000000000..738ceee5293
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_child.html
@@ -0,0 +1,14 @@
+<body>
+    Child.
+    <iframe id="grandchild" src="change_grandchild.html"></iframe>
+</body>
+<script>
+    var timer = window.setInterval(poll, 100);
+    function poll() {
+        if (document.body.getAttribute("data-contains-grandchild")) {
+            var grandchild = document.getElementById("grandchild");
+            window.frameElement.parentNode.appendChild(grandchild);
+            window.clearTimeout(timer);
+        }
+    }
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_grandchild.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_grandchild.html
new file mode 100644
index 00000000000..885622c2b4b
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_grandchild.html
@@ -0,0 +1,4 @@
+<body>Grandchild.</body>
+<script>
+    window.frameElement.parentNode.setAttribute("data-contains-grandchild", true);
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_parentage.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_parentage.html
new file mode 100644
index 00000000000..1d62ccc4806
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/change_parentage.html
@@ -0,0 +1,22 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Change the frame heriarchy</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+  <iframe src="change_child.html"></iframe>
+</body>
+<script>
+    async_test(function(t) {
+        var timer = window.setInterval(t.step_func(poll), 100);
+        function poll() {
+            // We wait for the grandchild's script to set the custom attribtue.
+            // Note that if this test passes, the grandchild's script must have been run twice,
+            // once to trigger the move from the child to here, and once to pass this test.
+            if (document.body.getAttribute("data-contains-grandchild")) {
+                window.clearTimeout(timer);
+                t.done();
+            }
+        }
+    });
+</script>
diff --git a/tests/wpt/mozilla/tests/mozilla/iframe/iframe_harness.js b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_harness.js
similarity index 100%
rename from tests/wpt/mozilla/tests/mozilla/iframe/iframe_harness.js
rename to tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/iframe_harness.js
diff --git a/tests/wpt/mozilla/tests/mozilla/iframe/same_origin_child.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/same_origin_child.html
similarity index 100%
rename from tests/wpt/mozilla/tests/mozilla/iframe/same_origin_child.html
rename to tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/same_origin_child.html
diff --git a/tests/wpt/mozilla/tests/mozilla/iframe/same_origin_grandchild.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/same_origin_grandchild.html
similarity index 100%
rename from tests/wpt/mozilla/tests/mozilla/iframe/same_origin_grandchild.html
rename to tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/same_origin_grandchild.html
diff --git a/tests/wpt/mozilla/tests/mozilla/iframe/same_origin_parentage.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/same_origin_parentage.html
similarity index 100%
rename from tests/wpt/mozilla/tests/mozilla/iframe/same_origin_parentage.html
rename to tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/same_origin_parentage.html
diff --git a/tests/wpt/mozilla/tests/mozilla/iframe/stash.py b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/stash.py
similarity index 100%
rename from tests/wpt/mozilla/tests/mozilla/iframe/stash.py
rename to tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/stash.py
