cleanup patch generation to preseve comments and remove @patch

test/dart_codegen/expect/core/string.dart

Index: test/dart_codegen/expect/core/string.dart
diff --git a/test/dart_codegen/expect/core/string.dart b/test/dart_codegen/expect/core/string.dart
index 352197d97d66d3e1b5dcd5638dc109054545623d..62925b967d407684cf7a547f0ace6c7cf056f710 100644
--- a/test/dart_codegen/expect/core/string.dart
+++ b/test/dart_codegen/expect/core/string.dart
@@ -1,16 +1,16 @@
 part of dart.core;
 
 abstract class String implements Comparable<String>, Pattern {
-  @patch factory String.fromCharCodes(Iterable<int> charCodes,
+  factory String.fromCharCodes(Iterable<int> charCodes,
       [int start = 0, int end]) {
     if (charCodes is! JSArray) {
       return ((__x36) => DDC$RT.cast(__x36, dynamic, String, "CastGeneral",
-          """line 99, column 15 of dart:core/string.dart: """, __x36 is String,
+          """line 118, column 15 of dart:core/string.dart: """, __x36 is String,
           true))(_stringFromIterable(charCodes, start, end));
     }
     List list = DDC$RT.cast(charCodes, DDC$RT.type((Iterable<int> _) {}),
         DDC$RT.type((List<dynamic> _) {}), "CastGeneral",
-        """line 102, column 18 of dart:core/string.dart: """,
+        """line 121, column 18 of dart:core/string.dart: """,
         charCodes is List<dynamic>, true);
     int len = list.length;
     if (start < 0 || start > len) {
@@ -25,15 +25,15 @@ abstract class String implements Comparable<String>, Pattern {
       list = list.sublist(start, end);
     }
     return ((__x37) => DDC$RT.cast(__x37, dynamic, String, "CastGeneral",
-        """line 116, column 13 of dart:core/string.dart: """, __x37 is String,
+        """line 135, column 13 of dart:core/string.dart: """, __x37 is String,
         true))(Primitives.stringFromCharCodes(list));
   }
-  @patch factory String.fromCharCode(int charCode) {
+  factory String.fromCharCode(int charCode) {
     return ((__x38) => DDC$RT.cast(__x38, dynamic, String, "CastGeneral",
-        """line 121, column 13 of dart:core/string.dart: """, __x38 is String,
+        """line 149, column 13 of dart:core/string.dart: """, __x38 is String,
         true))(Primitives.stringFromCharCode(charCode));
   }
-  @patch factory String.fromEnvironment(String name, {String defaultValue}) {
+  factory String.fromEnvironment(String name, {String defaultValue}) {
     throw new UnsupportedError(
         'String.fromEnvironment can only be used as a const constructor');
   }
@@ -117,7 +117,7 @@ class RuneIterator implements BidirectionalIterator<int> {
     }
   }
   int get rawIndex => ((__x39) => DDC$RT.cast(__x39, dynamic, int,
-      "CastGeneral", """line 645, column 24 of dart:core/string.dart: """,
+      "CastGeneral", """line 690, column 24 of dart:core/string.dart: """,
       __x39 is int, true))((_position != _nextPosition) ? _position : null);
   void set rawIndex(int rawIndex) {
     RangeError.checkValidIndex(rawIndex, string, "rawIndex");
@@ -131,7 +131,7 @@ class RuneIterator implements BidirectionalIterator<int> {
     _currentCodePoint = null;
   }
   int get current => DDC$RT.cast(_currentCodePoint, num, int, "CastGeneral",
-      """line 682, column 23 of dart:core/string.dart: """,
+      """line 727, column 23 of dart:core/string.dart: """,
       _currentCodePoint is int, true);
   int get currentSize => _nextPosition - _position;
   String get currentAsString {