[dart2js] Add missing debugName parameter to Isolate.spawn.

Fixes: https://github.com/dart-lang/sdk/issues/43581
Change-Id: I8d9517f04694e81c04d2eda7e743d85347cc423c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164940
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Mayank Patke <fishythefish@google.com>

sdk/lib/_internal/js_runtime/lib/isolate_patch.dart

@@ -41,7 +41,8 @@ class Isolate {
       {bool paused = false,
       bool errorsAreFatal = true,
       SendPort? onExit,
-      SendPort? onError}) {
+      SendPort? onError,
+      String? debugName}) {
     throw new UnsupportedError("Isolate.spawn");
   }