Issue 21613. Fix for renaming FieldFormalParameterElement.

pkg/analysis_server/lib/src/edit/edit_domain.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.
 
 library edit.domain;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/collections.dart';
@@ skipping 354 matching lines @@
           searchEngine,
           context,
           source);
     }
     if (kind == RefactoringKind.RENAME) {
       List<AstNode> nodes = server.getNodesAtOffset(file, offset);
       List<Element> elements = server.getElementsOfNodes(nodes, offset);
       if (nodes.isNotEmpty && elements.isNotEmpty) {
         AstNode node = nodes[0];
         Element element = elements[0];
+        if (element is FieldFormalParameterElement) {
+          element = (element as FieldFormalParameterElement).field;
+        }
         // climb from "Class" in "new Class()" to "new Class()"
         if (node.parent is TypeName &&
             node.parent.parent is ConstructorName &&
             node.parent.parent.parent is InstanceCreationExpression) {
           InstanceCreationExpression creation = node.parent.parent.parent;
           node = creation;
           element = creation.staticElement;
         }
         // do create the refactoring
         refactoring = new RenameRefactoring(searchEngine, element);
@@ skipping 114 matching lines @@
     }
     if (refactoring is RenameRefactoring) {
       RenameRefactoring renameRefactoring = refactoring;
       RenameOptions renameOptions = params.options;
       renameRefactoring.newName = renameOptions.newName;
       return renameRefactoring.checkNewName();
     }
     return new RefactoringStatus();
   }
 }