cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/core/regexp.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.core;
 
 /**
  * A result from searching within a string.
  *
  * A Match or an [Iterable] of Match objects is returned from [Pattern]
@@ skipping 100 matching lines @@
  * a string.
  *
  * The following example finds all matches of a regular expression in
  * a string.
  *
  *     RegExp exp = new RegExp(r"(\w+)");
  *     String str = "Parse my string";
  *     Iterable<Match> matches = exp.allMatches(str);
  */
 abstract class RegExp implements Pattern {
-  @patch
+  /**
+   * Constructs a regular expression.
+   *
+   * Throws a [FormatException] if [source] is not valid regular
+   * expression syntax.
+   */
   factory RegExp(String source,
                        {bool multiLine: false,
                         bool caseSensitive: true})
     => new JSSyntaxRegExp(source,
                           multiLine: multiLine,
                           caseSensitive: caseSensitive);
 
   /**
    * Searches for the first match of the regular expression
    * in the string [input]. Returns `null` if there is no match.
@@ skipping 33 matching lines @@
 
   /**
    * Whether this regular expression is case sensitive.
    *
    * If the regular expression is not case sensitive, it will match an input
    * letter with a pattern letter even if the two letters are different case
    * versions of the same letter.
    */
   bool get isCaseSensitive;
 }