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

pkg/kernel/lib/target/flutter.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.target.flutter;
 
 import '../ast.dart';
+import '../core_types.dart';
 import '../transformations/continuation.dart' as cont;
 import '../transformations/erasure.dart';
+import '../transformations/mixin_full_resolution.dart' as mix;
 import '../transformations/sanitize_for_vm.dart';
-import '../transformations/mixin_full_resolution.dart' as mix;
 import '../transformations/setup_builtin_library.dart' as setup_builtin_library;
 import 'targets.dart';
 
 class FlutterTarget extends Target {
   final TargetFlags flags;
 
   FlutterTarget(this.flags);
 
   bool get strongMode => flags.strongMode;
 
@@ skipping 21 matching lines @@
         'dart:_vmservice',
         'dart:_builtin',
         'dart:nativewrappers',
         'dart:io',
 
         // Required for flutter.
         'dart:ui',
         'dart:vmservice_sky',
       ];
 
-  void performModularTransformations(Program program) {
-    mix.transformLibraries(this, program.libraries);
+  void performModularTransformations(CoreTypes coreTypes, Program program) {
+    mix.transformLibraries(this, coreTypes, program.libraries);
   }
 
-  void performGlobalTransformations(Program program) {
-    cont.transformProgram(program);
+  void performGlobalTransformations(CoreTypes coreTypes, Program program) {
+    cont.transformProgram(coreTypes, program);
 
     // Repair `_getMainClosure()` function in dart:{_builtin,ui} libraries.
     setup_builtin_library.transformProgram(program);
     setup_builtin_library.transformProgram(program, libraryUri: 'dart:ui');
 
     if (strongMode) {
       new Erasure().transform(program);
     }
 
     new SanitizeForVM().transform(program);
   }
 
   @override
   Expression instantiateInvocation(Member target, Expression receiver,
       String name, Arguments arguments, int offset, bool isSuper) {
     // TODO(ahe): This should probably return the same as VmTarget does.
     return new InvalidExpression();
   }
 }