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diff --git a/testing/web-platform/tests/html/semantics/embedded-content/the-object-element/object-fallback-failed-cross-origin-navigation.sub.html b/testing/web-platform/tests/html/semantics/embedded-content/the-object-element/object-fallback-failed-cross-origin-navigation.sub.html
new file mode 100644
index 0000000000..09061e0349
--- /dev/null
+++ b/testing/web-platform/tests/html/semantics/embedded-content/the-object-element/object-fallback-failed-cross-origin-navigation.sub.html
@@ -0,0 +1,68 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test that &lt;object&gt; renders its own fallback.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<script>
+  const URIS = [
+    // The host exists but the resource is unavailable.
+    "http://{{hosts[alt][www]}}:{{ports[http][0]}}/foo.html",
+    // The destination does not even exist and the navigation fails.
+    "http://{{hosts[alt][nonexistent]}}:{{ports[http][0]}}/foo.html",
+  ];
+
+  // Create an <object> with some fallback content.
+  function create_object_with_fallback(url, t) {
+    var object = document.createElement("object");
+    var fallback = document.createElement("button");
+    fallback.textContent = "FALLBACK CONTENT";
+    object.appendChild(fallback);
+    object.data = url;
+    object.type = "text/html";
+    let promise = new Promise(resolve => {
+      object.addEventListener("load", t.unreached_func("Should never reach the load event"), {once: true});
+      object.addEventListener("error", () => resolve(object), {once: true});
+    });
+    document.body.appendChild(object);
+    t.add_cleanup(() => object.remove());
+    return promise;
+  }
+
+  function area(el) {
+    let bounds = el.getBoundingClientRect();
+    return bounds.width * bounds.height;
+  }
+
+  for (let uri of URIS) {
+    promise_test(async(t) => {
+      let object = await create_object_with_fallback(uri, t);
+
+      // XXX In Chrome this is needed, fallback doesn't seem to be ready after
+      // the error event, which seems weird/odd.
+      await new Promise(resolve => requestAnimationFrame(resolve));
+
+      assert_true(area(object.firstChild) > 0, "Should be showing fallback");
+
+      // Per https://html.spec.whatwg.org/#the-object-element:
+      //
+      //     The object element can represent an external resource, which,
+      //     depending on the type of the resource, will either be treated as
+      //     image, as a child browsing context, or as an external resource to
+      //     be processed by a plugin.
+      //
+      //     [...]
+      //
+      //     If the load failed (e.g. there was an HTTP 404 error, there was a
+      //     DNS error), fire an event named error at the element, then jump to
+      //     the step below labeled fallback.
+      //
+      // (And that happens before "Determine the resource type" which is what
+      // sets the nested browsing context).
+      //
+      // So the expected window.length is 0.
+      assert_equals(window.length, 0);
+    }, `Verify fallback content for failed cross-origin navigations is shown correctly: ${uri}`);
+  }
+</script>
+</body>