cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/core/errors.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;
 
 /**
  * Error objects thrown in the case of a program failure.
  *
  * An `Error` object represents a program failure that the programmer
@@ skipping 66 matching lines @@
   static String safeToString(Object object) {
     if (object is num || object is bool || null == object) {
       return object.toString();
     }
     if (object is String) {
       return _stringToSafeString(object);
     }
     return _objectToString(object);
   }
 
-  @patch
+  /** Convert string to a valid string literal with no control characters. */
   static String _stringToSafeString(String string) {
     return jsonEncodeNative(string);
   }
 
-  @patch
   static String _objectToString(Object object) {
     return Primitives.objectToString(object);
   }
 
-  @patch
   StackTrace get stackTrace => Primitives.extractStackTrace(this);
 }
 
 /**
  * Error thrown by the runtime system when an assert statement fails.
  */
 class AssertionError extends Error {
 }
 
 /**
@@ skipping 345 matching lines @@
                     Symbol memberName,
                     List positionalArguments,
                     Map<Symbol ,dynamic> namedArguments,
                     [List existingArgumentNames = null])
       : _receiver = receiver,
         _memberName = memberName,
         _arguments = positionalArguments,
         _namedArguments = namedArguments,
         _existingArgumentNames = existingArgumentNames;
 
-  @patch
   String toString() {
     StringBuffer sb = new StringBuffer();
     int i = 0;
     if (_arguments != null) {
       for (; i < _arguments.length; i++) {
         if (i > 0) {
           sb.write(", ");
         }
         sb.write(Error.safeToString(_arguments[i]));
       }
@@ skipping 123 matching lines @@
  * the first time it is read. If evaluating the initializer expression causes
  * another read of the variable, this error is thrown.
  */
 class CyclicInitializationError extends Error {
   final String variableName;
   CyclicInitializationError([this.variableName]);
   String toString() => variableName == null
       ? "Reading static variable during its initialization"
       : "Reading static variable '$variableName' during its initialization";
 }