cleanup patch generation to preseve comments and remove @patch

test/dart_codegen/expect/core/double.dart

Index: test/dart_codegen/expect/core/double.dart
diff --git a/test/dart_codegen/expect/core/double.dart b/test/dart_codegen/expect/core/double.dart
index d2a5cda49980da505c893a014fb248cb1867b86e..54c5b263de83e8a22c85b11ee0a0ea11fabc2f57 100644
--- a/test/dart_codegen/expect/core/double.dart
+++ b/test/dart_codegen/expect/core/double.dart
@@ -25,9 +25,9 @@ abstract class double extends num {
   double ceilToDouble();
   double truncateToDouble();
   String toString();
-  @patch static double parse(String source, [double onError(String source)]) {
+  static double parse(String source, [double onError(String source)]) {
     return ((__x10) => DDC$RT.cast(__x10, dynamic, double, "CastGeneral",
-        """line 173, column 12 of dart:core/double.dart: """, __x10 is double,
+        """line 206, column 12 of dart:core/double.dart: """, __x10 is double,
         true))(Primitives.parseDouble(source, onError));
   }
 }