Don't recreate CoreTypes in transformers. Pass it in.

pkg/kernel/lib/transformations/continuation.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 kernel.transformations.continuation;
 
 import 'dart:math' as math;
 
 import '../ast.dart';
 import '../core_types.dart';
 import '../visitor.dart';
 
 import 'async.dart';
 
 void transformLibraries(CoreTypes coreTypes, List<Library> libraries) {
   var helper = new HelperNodes.fromCoreTypes(coreTypes);
   var rewriter = new RecursiveContinuationRewriter(helper);
   for (var library in libraries) {
     rewriter.rewriteLibrary(library);
   }
 }
 
-Program transformProgram(Program program) {
-  var helper = new HelperNodes.fromProgram(program);
+Program transformProgram(CoreTypes coreTypes, Program program) {
+  var helper = new HelperNodes.fromCoreTypes(coreTypes);
   var rewriter = new RecursiveContinuationRewriter(helper);
   return rewriter.rewriteProgram(program);
 }
 
 class RecursiveContinuationRewriter extends Transformer {
   final HelperNodes helper;
   final VariableDeclaration asyncJumpVariable = new VariableDeclaration(
       ":await_jump_var",
       initializer: new IntLiteral(0));
   final VariableDeclaration asyncContextVariable =
@@ skipping 901 matching lines @@
         coreTypes.completerSyncConstructor,
         coreTypes.syncIterableDefaultConstructor,
         coreTypes.streamIteratorDefaultConstructor,
         coreTypes.futureMicrotaskConstructor,
         coreTypes.asyncStarStreamControllerDefaultConstructor,
         coreTypes.asyncThenWrapperHelperProcedure,
         coreTypes.asyncErrorWrapperHelperProcedure,
         coreTypes.awaitHelperProcedure,
         coreTypes);
   }
-
-  factory HelperNodes.fromProgram(Program program) {
-    var coreTypes = new CoreTypes(program);
-    return new HelperNodes.fromCoreTypes(coreTypes);
-  }
 }