Add ConstructorBodyEntity

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 '../constants/constructors.dart';
 import '../constants/expressions.dart';
@@ skipping 1394 matching lines @@
   /// `true` if this constructor is `String.fromEnvironment`.
   bool get isStringFromEnvironmentConstructor;
 
   /// Use [enclosingClass] instead.
   @deprecated
   get enclosingElement;
 }
 
 /// JavaScript backend specific element for the body of constructor.
 // TODO(johnniwinther): Remove this class from the element model.
-abstract class ConstructorBodyElement extends MethodElement {
+abstract class ConstructorBodyElement extends MethodElement
+    implements ConstructorBodyEntity {
   ConstructorElement get constructor;
 }
 
 /// [GenericElement] defines the common interface for generic functions and
 /// [TypeDeclarationElement].
 abstract class GenericElement extends Element implements AstElement {
   /// Do not use [computeType] outside of the resolver.
   ///
   /// Trying to access a type that has not been computed in resolution is an
   /// error and calling [computeType] covers that error.
@@ skipping 473 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;
 }