Implement removal of overridden instance methods.

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

 // Copyright (c) 2013, 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.modelx;
 
 import 'elements.dart';
 import '../constants/expressions.dart';
 import '../helpers/helpers.dart';  // Included for debug helpers.
 import '../tree/tree.dart';
@@ skipping 249 matching lines @@
 
   TreeElements get treeElements => analyzableElement.treeElements;
 
   AnalyzableElement get analyzableElement {
     Element element = outermostEnclosingMemberOrTopLevel;
     if (element.isAbstractField || element.isPrefix) return element.library;
     return element;
   }
 
   DeclarationSite get declarationSite => null;
+
+  void reuseElement() {
+    throw "reuseElement isn't implemented on ${runtimeType}.";
+  }
 }
 
 class ErroneousElementX extends ElementX implements ErroneousElement {
   final MessageKind messageKind;
   final Map messageArguments;
 
   ErroneousElementX(this.messageKind, this.messageArguments,
                     String name, Element enclosing)
       : super(name, ElementKind.ERROR, enclosing);
 
@@ skipping 2432 matching lines @@
   AstElement get definingElement;
 
   bool get hasResolvedAst => definingElement.hasTreeElements;
 
   ResolvedAst get resolvedAst {
     return new ResolvedAst(declaration,
         definingElement.node, definingElement.treeElements);
   }
 
 }