cleanup patch generation to preseve comments and remove @patch

test/dart_codegen/expect/core/stopwatch.dart

 part of dart.core;
 
 class Stopwatch {
   int get frequency => _frequency;
   num _start;
   num _stop;
   Stopwatch() {
     _initTicker();
   }
   void start() {
@@ skipping 28 matching lines @@
     return new Duration(microseconds: elapsedMicroseconds);
   }
   int get elapsedMicroseconds {
     return (elapsedTicks * 1000000) ~/ frequency;
   }
   int get elapsedMilliseconds {
     return (elapsedTicks * 1000) ~/ frequency;
   }
   bool get isRunning => _start != null && _stop == null;
   static int _frequency;
-  @patch static void _initTicker() {
+  static void _initTicker() {
     Primitives.initTicker();
     _frequency = DDC$RT.cast(Primitives.timerFrequency, dynamic, int,
-        "CastGeneral", """line 140, column 18 of dart:core/stopwatch.dart: """,
+        "CastGeneral", """line 143, column 18 of dart:core/stopwatch.dart: """,
         Primitives.timerFrequency is int, true);
   }
-  @patch static int _now() => ((__x35) => DDC$RT.cast(__x35, dynamic, int,
-      "CastGeneral", """line 143, column 24 of dart:core/stopwatch.dart: """,
+  static int _now() => ((__x35) => DDC$RT.cast(__x35, dynamic, int,
+      "CastGeneral", """line 145, column 24 of dart:core/stopwatch.dart: """,
       __x35 is int, true))(Primitives.timerTicks());
 }