cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/core/bool.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;
 
 /**
  * The reserved words [:true:] and [:false:] denote objects that are the only
  * instances of this class.
  *
  * It is a compile-time error for a class to attempt to extend or implement
  * bool.
  */
 class bool {
-  @patch
+  /**
+   * Returns the boolean value of the environment declaration [name].
+   *
+   * The boolean value of the declaration is `true` if the declared value is
+   * the string `"true"`, and `false` if the value is `"false"`.
+   *
+   * In all other cases, including when there is no declaration for `name`,
+   * the result is the [defaultValue].
+   *
+   * Example:
+   *
+   *     const loggingFlag = const bool.fromEnvironment("logging");
+   *
+   * If you want to use a different truth-string, you can use the
+   * [String.fromEnvironment] constructor directly:
+   *
+   *     const isLoggingOn = (const String.fromEnvironment("logging") == "on");
+   */
   factory bool.fromEnvironment(String name, {bool defaultValue: false}) {
     throw new UnsupportedError(
         'bool.fromEnvironment can only be used as a const constructor');
   }
 
   /**
    * Returns [:"true":] if the receiver is [:true:], or [:"false":] if the
    * receiver is [:false:].
    */
   String toString() {
     return this ? "true" : "false";
   }
 }