Fix a batch of DDC SDK compile errors.

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 20 matching lines @@
    *
    * Example:
    *
    *     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");
    */
+  // The .fromEnvironment() constructors are special in that we do not want
+  // users to call them using "new". We prohibit that by giving them bodies
+  // that throw, even though const constructors are not allowed to have bodies.
+  // Disable those static errors.
+  //ignore: const_constructor_with_body
+  //ignore: const_factory
   external const factory bool.fromEnvironment(String name,
       {bool defaultValue: false});
 
   external int get hashCode;
 
   /**
    * Returns [:"true":] if the receiver is [:true:], or [:"false":] if the
    * receiver is [:false:].
    */
   String toString() {
     return this ? "true" : "false";
   }
 }