Use entities in impact transformers.

pkg/compiler/lib/src/kernel/world_builder.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 file.
 
 library dart2js.kernel.world_builder;
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/backend_api.dart';
@@ skipping 563 matching lines @@
   bool isSubtype(DartType a, DartType b) {
     throw new UnimplementedError('KernelElementEnvironment.isSubtype');
   }
 
   @override
   FunctionType getFunctionType(KFunction function) {
     throw new UnimplementedError('KernelElementEnvironment.getFunctionType');
   }
 
   @override
+  FunctionType getLocalFunctionType(Local function) {
+    throw new UnimplementedError(
+        'KernelElementEnvironment.getLocalFunctionType');
+  }
+
+  @override
+  DartType getUnaliasedType(DartType type) => type;
+
+  @override
   ConstructorEntity lookupConstructor(ClassEntity cls, String name,
       {bool required: false}) {
     ConstructorEntity constructor = worldBuilder.lookupConstructor(cls, name);
     if (constructor == null && required) {
       throw new SpannableAssertionFailure(CURRENT_ELEMENT_SPANNABLE,
           "The constructor $name was not found in class '${cls.name}'.");
     }
     return constructor;
   }
 
@@ skipping 304 matching lines @@
   }
 
   InterfaceType getMixinTypeForClass(KClass cls) {
     KClassEnv env = builder._classEnvs[cls.classIndex];
     ir.Supertype mixedInType = env.cls.mixedInType;
     if (mixedInType == null) return null;
     return builder.createInterfaceType(
         mixedInType.classNode, mixedInType.typeArguments);
   }
 }