cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/async/schedule_microtask.dart

Index: test/generated_sdk/lib/async/schedule_microtask.dart
diff --git a/test/generated_sdk/lib/async/schedule_microtask.dart b/test/generated_sdk/lib/async/schedule_microtask.dart
index 4325f785f9c73dddee66496a7c623a66baf200b5..6bbe56c74657b6486d0827e00e9804962d338762 100644
--- a/test/generated_sdk/lib/async/schedule_microtask.dart
+++ b/test/generated_sdk/lib/async/schedule_microtask.dart
@@ -135,7 +135,7 @@ void scheduleMicrotask(void callback()) {
 }
 
 class _AsyncRun {
-  @patch
+  /** Schedule the given callback before any other event in the event-loop. */
   static void _scheduleImmediate(void callback()) {
     scheduleImmediateClosure(callback);
   }