TBR: Fix the build

pkg/analyzer2dart/lib/src/modely.dart

 // Copyright (c) 2014, 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.
 
 part of analyzer2dart.element_converter;
 
 
 /// Base [dart2js.Element] implementation for converted analyzer elements.
 class ElementY extends dart2js.Element {
   final ElementConverter converter;
@@ skipping 666 matching lines @@
   String get nativeTagInfo => unsupported('nativeTagInfo');
 
   @override
   void reverseBackendMembers() => unsupported('reverseBackendMembers');
 
   @override
   dart2js.ClassElement get superclass => unsupported('superclass');
 
   @override
   int get supertypeLoadState => unsupported('supertypeLoadState');
+
+  @override
+  dart2js.ConstructorElement lookupDefaultConstructor() => unsupported('lookupDefaultConstructor');
 }
 
 class TypedefElementY extends TypeDeclarationElementY
     implements dart2js.TypedefElement {
 
   analyzer.FunctionTypeAliasElement get element => super.element;
 
   dart2js.ElementKind get kind => dart2js.ElementKind.TYPEDEF;
 
   TypedefElementY(ElementConverter converter,
@@ skipping 136 matching lines @@
 
   @override
   get effectiveTarget => unsupported('effectiveTarget');
 
   @override
   get immediateRedirectionTarget => unsupported('immediateRedirectionTarget');
 
   @override
   get nestedClosures => unsupported('nestedClosures');
 }