Test is an old workaround is still necessary

pkgs/test/tool/host.dart

diff --git a/pkgs/test/tool/host.dart b/pkgs/test/tool/host.dart
index 23d83ae..d6bb00e 100644
--- a/pkgs/test/tool/host.dart
+++ b/pkgs/test/tool/host.dart
@@ -237,13 +237,8 @@
       // This message indicates that the iframe is actively listening for
       // events, so the message channel's second port can now be transferred.
       channel.port2.start();
-      // TODO(#1758): This is a work around for a crash in package:build.
-      js_util.callMethod(
-          js_util.getProperty(iframe, 'contentWindow'), 'postMessage', [
-        'port',
-        dom.window.location.origin,
-        [channel.port2]
-      ]);
+      iframe.contentWindow
+          .postMessage('port', dom.window.location.origin, [channel.port2]);
       readyCompleter.complete();
     } else if (message.data['exception'] == true) {
       // This message from `dart.js` indicates that an exception occurred