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

pkg/front_end/lib/src/fasta/fasta.dart

 // Copyright (c) 2016, 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.
 
 library fasta;
 
 import 'dart:async' show Future;
 
 import 'dart:convert' show JSON;
 
@@ skipping 251 matching lines @@
     await kernelTarget.writeDepsFile(output, depsFile,
         extraDependencies: extraDependencies);
   });
 }
 
 /// Load the [Program] from the given [uri] and append its libraries
 /// to the [dillTarget].
 void _appendDillForUri(DillTarget dillTarget, Uri uri) {
   var bytes = new File.fromUri(uri).readAsBytesSync();
   var platformProgram = loadProgramFromBytes(bytes);
+  platformProgram.unbindCanonicalNames();
   dillTarget.loader.appendLibraries(platformProgram);
 }
 
 // TODO(ahe): https://github.com/dart-lang/sdk/issues/28316
 class ByteSink implements Sink<List<int>> {
   final BytesBuilder builder = new BytesBuilder();
 
   void add(List<int> data) {
     builder.add(data);
   }
 
   void close() {
     // Nothing to do.
   }
 }