Make the VM's dart:core and dart:async library patches clean.

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.
  *
@@ skipping 23 matching lines @@
    *     const loggingFlag = const bool.fromEnvironment("logging");
    *
    * If you want to use a different truth-string than `"true"`, you can use the
    * [String.fromEnvironment] constructor directly:
    *
    *     const isLoggingOn = (const String.fromEnvironment("logging") == "on");
    */
   external const factory bool.fromEnvironment(String name,
                                               {bool defaultValue: false});
 
+  // TODO: Doc comment please.

[Lasse Reichstein Nielsen, 2016/12/08 12:25:32]

Shouldn't be necessary. It satisfies the requirements stated in Object.hashCode,
and we don't want to commit to any further details.

[Kevin Millikin (Google), 2016/12/09 08:38:59]

Done.

+  external int get hashCode;
+
   /**
    * Returns [:"true":] if the receiver is [:true:], or [:"false":] if the
    * receiver is [:false:].
    */
   String toString() {
     return this ? "true" : "false";
   }
 }