diff --git a/pkgs/test/lib/dart.js b/pkgs/test/lib/dart.js
index a3cc30286..4a090ef3e 100644
--- a/pkgs/test/lib/dart.js
+++ b/pkgs/test/lib/dart.js
@@ -12,6 +12,7 @@ window.onload = function() {
 // This mimics a MultiChannel-formatted message.
 var sendLoadException = function(message) {
   window.parent.postMessage({
+    // TODO: https://github.com/dart-lang/test/issues/2065 -  remove href
     "href": window.location.href,
     "data": [0, {"type": "loadException", "message": message}],
     "exception": true,
diff --git a/pkgs/test/lib/src/runner/browser/dom.dart b/pkgs/test/lib/src/runner/browser/dom.dart
index 48906f693..477158baa 100644
--- a/pkgs/test/lib/src/runner/browser/dom.dart
+++ b/pkgs/test/lib/src/runner/browser/dom.dart
@@ -11,6 +11,7 @@ import 'package:js/js.dart';
 class Window extends EventTarget {}
 
 extension WindowExtension on Window {
+  external Window get parent;
   external Location get location;
   CSSStyleDeclaration? getComputedStyle(Element elt, [String? pseudoElt]) =>
       js_util.callMethod(this, 'getComputedStyle', <Object>[
@@ -135,8 +136,18 @@ extension MessageEventExtension on MessageEvent {
   external String get origin;
   List<MessagePort> get ports =>
       js_util.getProperty<List>(this, 'ports').cast<MessagePort>();
+
+  /// The source may be a `WindowProxy`, a `MessagePort`, or a `ServiceWorker`.
+  ///
+  /// When a message is sent from an iframe through `window.parent.postMessage`
+  /// the source will be a `WindowProxy` which has the same methods as [Window].
+  external MessageEventSource source;
 }
 
+@JS()
+@staticInterop
+class MessageEventSource {}
+
 @JS()
 @staticInterop
 class Location {}
diff --git a/pkgs/test/lib/src/runner/browser/post_message_channel.dart b/pkgs/test/lib/src/runner/browser/post_message_channel.dart
index e24afeb1a..55a602076 100644
--- a/pkgs/test/lib/src/runner/browser/post_message_channel.dart
+++ b/pkgs/test/lib/src/runner/browser/post_message_channel.dart
@@ -4,15 +4,10 @@
 
 import 'dart:js_util';
 
-import 'package:js/js.dart';
 import 'package:stream_channel/stream_channel.dart';
 
 import 'dom.dart' as dom;
 
-// Avoid using this from dart:html to work around dart-lang/sdk#32113.
-@JS('window.parent.postMessage')
-external void _postParentMessage(Object message, String targetOrigin);
-
 /// Constructs a [StreamChannel] wrapping [MessageChannel] communication with
 /// the host page.
 StreamChannel<Object?> postMessageChannel() {
@@ -50,8 +45,8 @@ StreamChannel<Object?> postMessageChannel() {
 
   // Send a ready message once we're listening so the host knows it's safe to
   // start sending events.
-  // TODO(nweiz): Stop manually adding href here once issue 22554 is fixed.
-  _postParentMessage(
+  // TODO: https://github.com/dart-lang/test/issues/2065 -  remove href
+  dom.window.parent.postMessage(
       jsify({'href': dom.window.location.href, 'ready': true}) as Object,
       dom.window.location.origin);
 
diff --git a/pkgs/test/tool/host.dart b/pkgs/test/tool/host.dart
index 3f833b6ec..ee24a1929 100644
--- a/pkgs/test/tool/host.dart
+++ b/pkgs/test/tool/host.dart
@@ -209,10 +209,11 @@ StreamChannel<dynamic> _connectToIframe(String url, int id) {
     // running, but it's good practice to check the origin anyway.
     var message = event as dom.MessageEvent;
     if (message.origin != dom.window.location.origin) return;
-
-    // TODO(nweiz): Stop manually checking href here once issue 22554 is
-    // fixed.
-    if (message.data['href'] != iframe.src) return;
+    // Disambiguate between frames for different test suites.
+    // Depending on the source type, the `location.href` may be missing.
+    var location = js_util.getProperty(message.source, 'location') as Object?;
+    if (location == null) return;
+    if (js_util.getProperty(location, 'href') != iframe.src) return;
 
     message.stopPropagation();