Resynthesize combinators for import/export directives from Kernel.

pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.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_library_builder;
 
 import 'package:front_end/src/fasta/dill/dill_library_builder.dart';
+import 'package:front_end/src/fasta/combinator.dart' as fasta;
 import 'package:front_end/src/fasta/export.dart';
 import 'package:front_end/src/fasta/import.dart';
 import 'package:kernel/ast.dart';
 
 import 'package:kernel/clone.dart' show CloneVisitor;
 
 import '../../scanner/token.dart' show Token;
 
 import '../fasta_codes.dart'
     show
@@ skipping 708 matching lines @@
       // Nothing needed.
     } else {
       unhandled("${builder.runtimeType}", "buildBuilder", builder.charOffset,
           builder.fileUri);
     }
   }
 
   @override
   Library build(LibraryBuilder coreLibrary) {
     super.build(coreLibrary);
+
+    List<Combinator> toKernelCombinators(
+        Iterable<fasta.Combinator> fastaCombinators) {
+      return fastaCombinators?.map((c) {
+        List<String> nameList = c.names.toList();
+        return c.isShow
+            ? new Combinator.show(nameList)
+            : new Combinator.hide(nameList);
+      })?.toList();
+    }
+
     for (Import import in imports) {
       var importedBuilder = import.imported;
       Library importedLibrary;
       if (importedBuilder is DillLibraryBuilder) {
         importedLibrary = importedBuilder.library;
       } else if (importedBuilder is KernelLibraryBuilder) {
         importedLibrary = importedBuilder.library;
       }
       if (importedLibrary != null) {
-        library.addDependency(
-            new LibraryDependency.import(importedLibrary, name: import.prefix));
+        library.addDependency(new LibraryDependency.import(importedLibrary,
+            name: import.prefix,
+            combinators: toKernelCombinators(import.combinators)));
       }
     }
-    for (Export import in exports) {
-      var exportedBuilder = import.exported;
+    for (Export export in exports) {
+      var exportedBuilder = export.exported;
       Library exportedLibrary;
       if (exportedBuilder is DillLibraryBuilder) {
         exportedLibrary = exportedBuilder.library;
       } else if (exportedBuilder is KernelLibraryBuilder) {
         exportedLibrary = exportedBuilder.library;
       }
       if (exportedLibrary != null) {
-        library.addDependency(new LibraryDependency.export(exportedLibrary));
+        library.addDependency(new LibraryDependency.export(exportedLibrary,
+            combinators: toKernelCombinators(export.combinators)));
       }
     }
     library.name = name;
     library.procedures.sort(compareProcedures);
     return library;
   }
 
   @override
   Builder buildAmbiguousBuilder(
       String name, Builder builder, Builder other, int charOffset,
@@ skipping 155 matching lines @@
           mixinApplicationClasses.putIfAbsent(name, () => builder);
       if (existing != builder) {
         part.scope.local.remove(name);
       }
     });
     super.includePart(part);
     nativeMethods.addAll(part.nativeMethods);
     boundlessTypeVariables.addAll(part.boundlessTypeVariables);
   }
 }