Transform async code only for source libraries.

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;
 
@@ skipping 22 matching lines @@
         Program,
         Source,
         StringLiteral,
         SuperInitializer,
         Throw,
         TypeParameter,
         VariableDeclaration,
         VariableGet,
         VoidType;
 
+import 'package:kernel/core_types.dart';

[ahe, 2017/05/24 12:15:55]

Please use show.

[scheglov, 2017/05/24 22:45:50]

Done.

 import 'package:kernel/transformations/erasure.dart' show Erasure;
 
 import 'package:kernel/transformations/continuation.dart' as transformAsync;
 
 import 'package:kernel/transformations/mixin_full_resolution.dart'
     show MixinFullResolution;
 
 import 'package:kernel/type_algebra.dart' show substitute;
 
 import '../source/source_loader.dart' show SourceLoader;
@@ skipping 610 matching lines @@
     new MixinFullResolution(backendTarget).transform(_program);
     ticker.logMs("Transformed mixin applications");
   }
 
   void otherTransformations() {
     // TODO(ahe): Don't generate type variables in the first place.
     if (!strongMode) {
       _program.accept(new Erasure());
       ticker.logMs("Erased type variables in generic methods");
     }
-    // TODO(kmillikin): Make this run on a per-method basis.

[ahe, 2017/05/24 12:15:55]

I think this TODO still applies.

[scheglov, 2017/05/24 22:45:50]

Done.

-    transformAsync.transformProgram(_program);
+    var coreTypes = new CoreTypes(_program);
+    transformAsync.transformLibraries(coreTypes, loader.libraries);
     ticker.logMs("Transformed async methods");
   }
 
   void verify() {
     var verifyErrors = verifyProgram(_program);
     errors.addAll(verifyErrors.map((error) => '$error'));
     ticker.logMs("Verified program");
   }
 
   /// Tree-shakes most code from the [dillTarget] by visiting all other
@@ skipping 28 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }