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

pkg/kernel/lib/transformations/mixin_full_resolution.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.mixin_full_resolution;
 
 import '../ast.dart';
 import '../class_hierarchy.dart';
 import '../clone.dart';
 import '../core_types.dart';
 import '../target/targets.dart' show NoneTarget, Target;
 import '../type_algebra.dart';
 
-Program transformProgram(Program program) {
-  new MixinFullResolution(new NoneTarget(null)).transform(program);
+Program transformProgram(CoreTypes coreTypes, Program program) {
+  new MixinFullResolution(new NoneTarget(null), coreTypes).transform(program);
   return program;
 }
 
 /// Replaces all mixin applications with regular classes, cloning all fields
 /// and procedures from the mixed-in class, cloning all constructors from the
 /// base class.
 ///
 /// Super calls (as well as super initializer invocations) are also resolved
 /// to their targets in this pass.
 class MixinFullResolution {
   final Target targetInfo;
 
+  final CoreTypes coreTypes;
   ClassHierarchy hierarchy;
-  CoreTypes coreTypes;
 
-  MixinFullResolution(this.targetInfo);
+  MixinFullResolution(this.targetInfo, this.coreTypes);
 
   void transform(Program program) {
     var transformedClasses = new Set<Class>();
 
     // Desugar all mixin application classes by copying in fields/methods from
     // the mixin and constructors from the base class.
     var processedClasses = new Set<Class>();
     for (var library in program.libraries) {
       if (library.isExternal) continue;
 
       for (var class_ in library.classes) {
         transformClass(processedClasses, transformedClasses, class_);
       }
     }
 
     hierarchy = new ClassHierarchy(program);
-    coreTypes = new CoreTypes(program);
 
     // Resolve all super call expressions and super initializers.
     for (var library in program.libraries) {
       if (library.isExternal) continue;
 
       for (var class_ in library.classes) {
         final bool hasTransformedSuperclass =
             transformedClasses.contains(class_.superclass);
 
         for (var procedure in class_.procedures) {
@@ skipping 274 matching lines @@
           return null;
         }
       }
 
       throw new Exception(
           'Could not find a generative constructor named "${constructor.name}" '
           'in lookup class "${lookupClass.name}"!');
     }
   }
 }