Disconnected <a> should not navigate

Follow-up tests for whatwg/html#2613.

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

@@ -0,0 +1,50 @@
+["a",
+ "area"].forEach(type => {
+
+  const followed = type === "a" ? true : false;
+  async_test(t => {
+    const target = document.createElement("iframe"),
+          link = document.createElement(type);
+    t.add_cleanup(() => target.remove());
+    target.name = "certifiedrandom" + type;
+    link.target = "certifiedrandom" + type;
+    link.href = "/";
+    document.body.appendChild(target);
+    target.onload = t.step_func(() => {
+      if(target.contentWindow.location.href === "about:blank")
+        return;
+      if(followed) {
+        assert_equals(target.contentWindow.location.pathname, "/");
+        t.done();
+      } else {
+        assert_unreached();
+      }
+    });
+    link.click();
+    t.step_timeout(() => {
+      if(followed) {
+        assert_unreached();
+      } else {
+        t.done();
+      }
+    }, 500);
+  }, "<" + type + "> that is not connected should " + (followed ? "" : "not ") + "be followed");
+
+  async_test(t => {
+    const target = document.createElement("iframe"),
+          doc = document.implementation.createDocument("", ""),
+          link = doc.createElementNS("http://www.w3.org/1999/xhtml", type);
+    t.add_cleanup(() => target.remove());
+    target.name = "certifiedrandom2" + type;
+    link.target = "certifiedrandom2" + type;
+    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);
+  }, "<" + type + "> that is from an inactive document should not be followed");
+});