Align semantics of getDefaultConstructor()

pkg/compiler/lib/src/elements/elements.dart

 // Copyright (c) 2012, 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 elements;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
 import '../constants/constructors.dart';
@@ skipping 1481 matching lines @@
   Element lookupMember(String memberName);
   Element lookupByName(Name memberName);
   Element lookupSuperByName(Name memberName);
 
   Element lookupLocalMember(String memberName);
   Element lookupBackendMember(String memberName);
   Element lookupSuperMember(String memberName);
 
   Element lookupSuperMemberInLibrary(String memberName, LibraryElement library);
 
+  // TODO(johnniwinther): Clean up semantics. Can the default constructor take
+  // optional arguments? Must it be resolved?
   ConstructorElement lookupDefaultConstructor();
   ConstructorElement lookupConstructor(String name);
 
   void forEachMember(void f(ClassElement enclosingClass, Element member),
       {bool includeBackendMembers: false,
       bool includeSuperAndInjectedMembers: false});
 
   void forEachInstanceField(
       void f(ClassElement enclosingClass, FieldElement field),
       {bool includeSuperAndInjectedMembers: false});
@@ skipping 331 matching lines @@
   /// by a field.
   bool get isDeclaredByField;
 
   /// Returns `true` if this member is abstract.
   bool get isAbstract;
 
   /// If abstract, [implementation] points to the overridden concrete member,
   /// if any. Otherwise [implementation] points to the member itself.
   Member get implementation;
 }