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

pkg/kernel/lib/target/vm.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.vm;
 
 import '../ast.dart';
 import '../class_hierarchy.dart';
 import '../core_types.dart';
 import '../transformations/continuation.dart' as cont;
 import '../transformations/erasure.dart';
@@ skipping 38 matching lines @@
         'dart:typed_data',
         'dart:vmservice_io',
         'dart:_vmservice',
         'dart:_builtin',
         'dart:nativewrappers',
         'dart:io',
       ];
 
   ClassHierarchy _hierarchy;
 
-  void performModularTransformations(Program program) {
-    var mixins = new mix.MixinFullResolution(this)..transform(program);
+  void performModularTransformations(CoreTypes coreTypes, Program program) {
+    var mixins = new mix.MixinFullResolution(this, coreTypes)
+      ..transform(program);
 
     _hierarchy = mixins.hierarchy;
   }
 
-  void performGlobalTransformations(Program program) {
-    var coreTypes = new CoreTypes(program);
-
+  void performGlobalTransformations(CoreTypes coreTypes, Program program) {
     if (strongMode) {
-      new InsertTypeChecks(hierarchy: _hierarchy, coreTypes: coreTypes)
+      new InsertTypeChecks(coreTypes, hierarchy: _hierarchy)
           .transformProgram(program);
-      new InsertCovarianceChecks(hierarchy: _hierarchy, coreTypes: coreTypes)
+      new InsertCovarianceChecks(coreTypes, hierarchy: _hierarchy)
           .transformProgram(program);
     }
 
     if (flags.treeShake) {
-      performTreeShaking(program);
+      performTreeShaking(coreTypes, program);
     }
 
-    cont.transformProgram(program);
+    cont.transformProgram(coreTypes, program);
 
     if (strongMode) {
       performErasure(program);
     }
 
     new SanitizeForVM().transform(program);
   }
 
-  void performTreeShaking(Program program) {
-    var coreTypes = new CoreTypes(program);
-    new TreeShaker(program,
+  void performTreeShaking(CoreTypes coreTypes, Program program) {
+    new TreeShaker(coreTypes, program,
             hierarchy: _hierarchy,
-            coreTypes: coreTypes,
             strongMode: strongMode,
             programRoots: flags.programRoots)
         .transform(program);
     _hierarchy = null; // Hierarchy must be recomputed.
   }
 
   void performErasure(Program program) {
     new Erasure().transform(program);
   }
 
@@ skipping 54 matching lines @@
     // this is currently only used in (statically resolved) no-such-method
     // handling, the current approach seems sufficient.
     return new MethodInvocation(
         new ListLiteral(elements)..fileOffset = charOffset,
         new Name("toList"),
         new Arguments(<Expression>[], named: <NamedExpression>[
           new NamedExpression("growable", new BoolLiteral(false))
         ]));
   }
 }