cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/core/string_buffer.dart

 // Copyright (c) 2011, 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 class for concatenating strings efficiently.
  *
  * Allows for the incremental building of a string using write*() methods.
  * The strings are concatenated to a single string only when [toString] is
  * called.
  */
 class StringBuffer implements StringSink {
 
-  @patch
+  /** Creates the string buffer with an initial content. */
   StringBuffer([Object content = ""]) : _contents = '$content';
 
-  @patch
+  /**
+   * Returns the length of the content that has been accumulated so far.
+   * This is a constant-time operation.
+   */
   int get length => _contents.length;
 
   /** Returns whether the buffer is empty. This is a constant-time operation. */
   bool get isEmpty => length == 0;
 
   /**
    * Returns whether the buffer is not empty. This is a constant-time
    * operation.
    */
   bool get isNotEmpty => !isEmpty;
 
-  @patch
+  /// Adds the contents of [obj], converted to a string, to the buffer.
   void write(Object obj) {
     _writeString('$obj');
   }
 
-  @patch
+  /// Adds the string representation of [charCode] to the buffer.
   void writeCharCode(int charCode) {
     _writeString(new String.fromCharCode(charCode));
   }
 
   void writeAll(Iterable objects, [String separator = ""]) {
     Iterator iterator = objects.iterator;
     if (!iterator.moveNext()) return;
     if (separator.isEmpty) {
       do {
         write(iterator.current);
       } while (iterator.moveNext());
     } else {
       write(iterator.current);
       while (iterator.moveNext()) {
         write(separator);
         write(iterator.current);
       }
     }
   }
 
   void writeln([Object obj = ""]) {
     write(obj);
     write("\n");
   }
 
-  @patch
+  /**
+   * Clears the string buffer.
+   */
   void clear() {
     _contents = "";
   }
 
-  @patch
+  /// Returns the contents of buffer as a concatenated string.
   String toString() => Primitives.flattenString(_contents);
 }