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

pkg/front_end/lib/src/fasta/kernel/kernel_target.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.kernel_target;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show File, IOSink;
 
@@ skipping 354 matching lines @@
     library.build(loader.coreLibrary);
     return link(<Library>[library.library]);
   }
 
   /// Creates a program by combining [libraries] with the libraries of
   /// `dillTarget.loader.program`.
   Program link(List<Library> libraries) {
     Map<String, Source> uriToSource =
         new Map<String, Source>.from(this.uriToSource);
 
-    final Program binary = dillTarget.loader.program;
-    if (binary != null) {
-      libraries.addAll(binary.libraries);
-      uriToSource.addAll(binary.uriToSource);
-    }
+    libraries.addAll(dillTarget.loader.libraries);
 
     // TODO(ahe): Remove this line. Kernel seems to generate a default line map
     // that used when there's no fileUri on an element. Instead, ensure all
     // elements have a fileUri.
     uriToSource[""] = new Source(<int>[0], const <int>[]);
-    Program program = new Program(libraries, uriToSource);
+    Program program = new Program(
+        nameRoot: dillTarget.nameRoot,

[Siggi Cherem (dart-lang), 2017/05/12 16:27:57]

I think I don't have the full picture yet.

I'm currently wondering whether we want to put nameRoot in dillTarget or
somewhere else. Maybe it will help if you could tell me how do you intend to use
the nameRoot afterwards?

In the current CL it is used here while linking. If it's just going to be used
here, I'd be inclined to move the declaration right here in KernelTarget or
consider passing it as an optional argument to the linking function.

[scheglov, 2017/05/12 17:15:16]

Done.

+        libraries: libraries,
+        uriToSource: uriToSource);
     if (loader.first != null) {
       Builder builder = loader.first.lookup("main", -1, null);
       if (builder is KernelProcedureBuilder) {
         program.mainMethod = builder.procedure;
       }
     }
     if (errors.isEmpty || dillTarget.isLoaded) {
       runLinkTransformations(program);
     }
     ticker.logMs("Linked program");
@@ skipping 322 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }