Introduce ConstructorEntity

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 1398 matching lines @@
 
 /// A top level, static or instance function.
 abstract class MethodElement extends FunctionElement
     implements MemberElement, FunctionEntity {}
 
 /// A local function or closure (anonymous local function).
 abstract class LocalFunctionElement extends FunctionElement
     implements LocalElement {}
 
 /// A constructor.
-abstract class ConstructorElement extends MethodElement {
+abstract class ConstructorElement extends MethodElement
+    implements ConstructorEntity {
   /// Returns `true` if [effectiveTarget] has been computed for this
   /// constructor.
   bool get hasEffectiveTarget;
 
   /// The effective target of this constructor, that is the non-redirecting
   /// constructor that is called on invocation of this constructor.
   ///
   /// Consider for instance this hierarchy:
   ///
   ///     class C { factory C.c() = D.d; }
@@ skipping 614 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;
 }