Add a way to use shared CanonicalName root to deserialize Program.

pkg/kernel/lib/testing/mock_sdk_program.dart

 // Copyright (c) 2017, 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.
 
 import 'package:kernel/ast.dart';
 
 /// Returns a [Program] object containing empty definitions of core SDK classes.
 Program createMockSdkProgram() {
   var coreLib = new Library(Uri.parse('dart:core'), name: 'dart.core');
   var asyncLib = new Library(Uri.parse('dart:async'), name: 'dart.async');
@@ skipping 45 matching lines @@
   addClass(coreLib, class_('double', supertype: num.asThisSupertype));
   addClass(coreLib, class_('Iterator', typeParameters: [typeParam('T')]));
   addClass(coreLib, class_('Symbol'));
   addClass(coreLib, class_('Type'));
   addClass(coreLib, class_('Function'));
   addClass(coreLib, class_('Invocation'));
   addClass(asyncLib, class_('Future', typeParameters: [typeParam('T')]));
   addClass(asyncLib, class_('Stream', typeParameters: [typeParam('T')]));
   addClass(internalLib, class_('Symbol'));
 
-  return new Program([coreLib, asyncLib, internalLib]);
+  return new Program(libraries: [coreLib, asyncLib, internalLib]);
 }