Test which document history.go(0) reloads

See whatwg/html#2436. Specified in whatwg/html#6315.

html/browsers/history/the-history-interface/history_go_zero_which_document.window.js

@@ -0,0 +1,27 @@
+// META: title=history.go(0) on an iframe must reload the iframe's document, not the parent document
+// META: script=/common/dispatcher/dispatcher.js
+// META: script=/common/utils.js
+// META: script=/html/browsers/browsing-the-web/remote-context-helper/resources/remote-context-helper.js
+
+promise_test(async () => {
+  const rcHelper = new RemoteContextHelper();
+  const main = await rcHelper.addWindow();
+  await main.addIframe();
+
+  await main.executeScript(() => {
+    window.didNotGetReloaded = true;
+
+    const iframe = document.querySelector("iframe");
+
+    // This goes beyond the original test case in https://github.com/whatwg/html/issues/2436, and
+    // tests where current realm != relevant realm. The spec says to use relevant realm so the
+    // result is still, iframe must reload, not parent.
+    History.prototype.go.call(iframe.contentWindow.history, 0);
+
+    return new Promise(resolve => {
+      iframe.addEventListener("load", resolve);
+    });
+  });
+
+  assert_true(await main.executeScript(() => window.didNotGetReloaded));
+});