cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/async/timer.dart

Index: test/generated_sdk/lib/async/timer.dart
diff --git a/test/generated_sdk/lib/async/timer.dart b/test/generated_sdk/lib/async/timer.dart
index d689f7b14f095aaf6d24254fc8b922fe5bc9eb77..5389e5adc1d0862240f67a1f0c2dd8883c6c1166 100644
--- a/test/generated_sdk/lib/async/timer.dart
+++ b/test/generated_sdk/lib/async/timer.dart
@@ -104,13 +104,11 @@ abstract class Timer {
    */
   bool get isActive;
 
-  @patch
   static Timer _createTimer(Duration duration, void callback()) {
     int milliseconds = duration.inMilliseconds;
     if (milliseconds < 0) milliseconds = 0;
     return new TimerImpl(milliseconds, callback);
   }
-  @patch
   static Timer _createPeriodicTimer(Duration duration,
                              void callback(Timer timer)) {
     int milliseconds = duration.inMilliseconds;