Run closed_world2_test using the normal compiler pipeline.

pkg/compiler/lib/src/kernel/element_map.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.element_map;
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/resolution.dart';
@@ skipping 107 matching lines @@
 
   ConstantEnvironment get constantEnvironment => _constantEnvironment;
 
   DartTypes get types => _types;
 
   @override
   native.BehaviorBuilder get nativeBehaviorBuilder => _nativeBehaviorBuilder;
 
   LibraryEntity lookupLibrary(Uri uri) {
     _KLibraryEnv libraryEnv = _env.lookupLibrary(uri);
+    if (libraryEnv == null) return null;
     return _getLibrary(libraryEnv.library, libraryEnv);
   }
 
   KLibrary _getLibrary(ir.Library node, [_KLibraryEnv libraryEnv]) {
     return _libraryMap.putIfAbsent(node, () {
       Uri canonicalUri = node.importUri;
       _libraryEnvs.add(libraryEnv ?? _env.lookupLibrary(canonicalUri));
       String name = node.name;
       if (name == null) {
         // Use the file name as script name.
@@ skipping 1125 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);
   }
 }