Disconnected <a> should still navigate

Follow-up test for whatwg/html#2613.

html/semantics/links/following-hyperlinks/activation-behavior.window.js

@@ -0,0 +1,35 @@
+async_test(t => {
+  const target = document.createElement("iframe"),
+        link = document.createElement("a");
+  t.add_cleanup(() => target.remove());
+  target.name = "certifiedrandom";
+  link.target = "certifiedrandom";
+  link.href = "/";
+  document.body.appendChild(target);
+  target.onload = t.step_func(() => {
+    if(target.contentWindow.location.href === "about:blank")
+      return;
+    assert_equals(target.contentWindow.location.pathname, "/");
+    t.done();
+  });
+  link.click();
+  t.step_timeout(() => assert_unreached(), 500);
+}, "<a> that is not connected should still be followed");
+
+async_test(t => {
+  const target = document.createElement("iframe"),
+        doc = document.implementation.createDocument("", ""),
+        link = doc.createElementNS("http://www.w3.org/1999/xhtml", "a");
+  t.add_cleanup(() => target.remove());
+  target.name = "certifiedrandom2";
+  link.target = "certifiedrandom2";
+  link.href = "/";
+  document.body.appendChild(target);
+  target.onload = t.step_func(() => {
+    if(target.contentWindow.location.href === "about:blank")
+      return;
+    assert_unreached();
+  });
+  link.click();
+  t.step_timeout(() => t.done(), 500);
+}, "<a> that is from an inactive document should not be followed");