Move `reify` to use fasta instead of dartk

pkg/kernel/test/closures/suite.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.md file.
 
 library test.kernel.closures.suite;
 
 import 'dart:async' show Future;
 
 import 'package:kernel/core_types.dart' show CoreTypes;
 
@@ skipping 12 matching lines @@
         WriteDill,
         ReadDill,
         Verify,
         Compile,
         CompileContext;
 
 const String STRONG_MODE = " strong mode ";
 
 class ClosureConversionContext extends ChainContext implements CompileContext {
   final bool strongMode;
+  Target get target => null;
 
   final List<Step> steps;
 
   ClosureConversionContext(this.strongMode, bool updateExpectations)
       : steps = <Step>[
           const Compile(),
           const Print(),
           const Verify(true),
           const ClosureConversion(),
           const Print(),
@@ skipping 34 matching lines @@
           .firstWhere((Library library) => library.importUri.scheme != "dart");
       closure_conversion.transformLibraries(coreTypes, <Library>[library]);
       return pass(program);
     } catch (e, s) {
       return crash(e, s);
     }
   }
 }
 
 main(List<String> arguments) => runMe(arguments, createContext, "testing.json");