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

pkg/front_end/lib/src/incremental_kernel_generator_impl.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 'dart:async';
 
 import 'package:front_end/file_system.dart';
 import 'package:front_end/incremental_kernel_generator.dart';
 import 'package:front_end/incremental_resolved_ast_generator.dart';
 import 'package:front_end/src/base/processed_options.dart';
@@ skipping 87 matching lines @@
       Uri fileUri = _uriTranslator.translate(absoluteUri);
       await _fsState.getFile(fileUri);
     }
   }
 
   /// Return the [DillTarget] that is used inside of [KernelTarget] to
   /// resynthesize SDK libraries.
   Future<DillTarget> _getSdkDillTarget() async {
     if (_sdkDillTarget == null) {
       _sdkDillTarget =
-          new DillTarget(new Ticker(isVerbose: false), _uriTranslator);
+          new DillTarget(null, new Ticker(isVerbose: false), _uriTranslator);
       // TODO(scheglov) Read the SDK kernel.
 //      _sdkDillTarget.read(options.sdkSummary);
 //      await _sdkDillTarget.writeOutline(null);
     } else {
 //      Program sdkProgram = _sdkDillTarget.loader.program;
 //      sdkProgram.visitChildren(new _ClearCanonicalNamesVisitor());
     }
     return _sdkDillTarget;
   }
 
   /// Refresh all the invalidated files and update dependencies.
   Future<Null> _refreshInvalidatedFiles() async {
     for (Uri fileUri in _invalidatedFiles) {
       FileState file = await _fsState.getFile(fileUri);
       await file.refresh();
     }
     _invalidatedFiles.clear();
   }
 }
 
 ///// Clears canonical names of [NamedNode] references.
 //class _ClearCanonicalNamesVisitor extends Visitor {
 //  defaultNode(Node node) {
 //    if (node is NamedNode) {
 //      node.reference.canonicalName = null;
 //    }
 //    node.visitChildren(this);
 //  }
 //}