cleanup patch generation to preseve comments and remove @patch

test/dart_codegen/expect/core/regexp.dart

Index: test/dart_codegen/expect/core/regexp.dart
diff --git a/test/dart_codegen/expect/core/regexp.dart b/test/dart_codegen/expect/core/regexp.dart
index fe2734a4ba5722dac2e94d6d47a19128b6731b9d..c933ec0f16b0fdd0732736a18c51cf2acdb72614 100644
--- a/test/dart_codegen/expect/core/regexp.dart
+++ b/test/dart_codegen/expect/core/regexp.dart
@@ -11,10 +11,10 @@ abstract class Match {
   Pattern get pattern;
 }
 abstract class RegExp implements Pattern {
-  @patch factory RegExp(String source,
+  factory RegExp(String source,
       {bool multiLine: false, bool caseSensitive: true}) => ((__x33) => DDC$RT
               .cast(__x33, dynamic, RegExp, "CastExact",
-                  """line 125, column 8 of dart:core/regexp.dart: """,
+                  """line 130, column 8 of dart:core/regexp.dart: """,
                   __x33 is RegExp, true))(new JSSyntaxRegExp(source,
           multiLine: multiLine, caseSensitive: caseSensitive));
   Match firstMatch(String input);