Register created closure class with the world.

pkg/compiler/lib/src/kernel/env.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.env;
 
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/clone.dart';
 import 'package:kernel/type_algebra.dart';
 
@@ skipping 143 matching lines @@
   Map<String, ir.Member> _constructorMap;
   Map<String, ir.Member> _memberMap;
   Map<String, ir.Member> _setterMap;
 
   ClassEnv(this.cls)
       // TODO(johnniwinther): Change this to use a property on [cls] when such
       // is added to kernel.
       : isUnnamedMixinApplication =
             cls.name.contains('+') || cls.name.contains('&');
 
+  // TODO(efortuna): This is gross because even though the closure class *has*
+  // members, we're not populating this because they aren't ir.Member types. :-(
+  ClassEnv.closureClass()
+      : cls = null,
+        isUnnamedMixinApplication = false,
+        _constructorMap = const <String, ir.Member>{},
+        _memberMap = const <String, ir.Member>{},
+        _setterMap = const <String, ir.Member>{};
+
   /// Copied from 'package:kernel/transformations/mixin_full_resolution.dart'.
   ir.Constructor _buildForwardingConstructor(
       CloneVisitor cloner, ir.Constructor superclassConstructor) {
     var superFunction = superclassConstructor.function;
 
     // We keep types and default values for the parameters but always mark the
     // parameters as final (since we just forward them to the super
     // constructor).
     ir.VariableDeclaration cloneVariable(ir.VariableDeclaration variable) {
       ir.VariableDeclaration clone = cloner.clone(variable);
@@ skipping 256 matching lines @@
       }
     }
     return _constant;
   }
 
   @override
   FieldData copy() {
     return new FieldData(node);
   }
 }