Fix a type error in reify/transformation/builder.dart.

pkg/kernel/lib/transformations/reify/transformation/builder.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.reify.transformation.builder;
 
 import '../asts.dart';
 import 'package:kernel/ast.dart';
 import 'dart:collection' show LinkedHashMap;
 import 'binding.dart' show RuntimeLibrary;
@@ skipping 425 matching lines @@
             .toList();
         callableType = new FunctionType(
             positionalArguments, function.returnType,
             namedParameters: namedParameters,
             requiredParameterCount: function.requiredParameterCount);
       }
       statements.add(new ExpressionStatement(createCallInit(
           parameter,
           id,
           cls.supertype?.asInterfaceType,
-          cls.implementedTypes.map((Supertype type) => type?.asInterfaceType),
+          cls.implementedTypes
+              .map((Supertype type) => type?.asInterfaceType)
+              .toList(),
           callableType)));
     });
 
     statements.add(new ReturnStatement(new VariableGet(parameter)));
 
     Expression function = new FunctionExpression(new FunctionNode(
         new Block(statements),
         positionalParameters: <VariableDeclaration>[parameter],
         returnType: declarationType));
 
@@ skipping 45 matching lines @@
     declarations.type = declarationType;
   }
 
   Procedure createGetter(
       Name name, Expression expression, Class cls, DartType type) {
     return new Procedure(name, ProcedureKind.Getter,
         new FunctionNode(new ReturnStatement(expression), returnType: type),
         fileUri: cls.fileUri);
   }
 }