Issue 21613. Fix for renaming FieldFormalParameterElement.

pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart

Index: pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
diff --git a/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart b/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
index e88a94c2de37f762d16246d4175135bc516feaa4..5bcee178dcc0239eed375dd1a54e88f7c0c7d635 100644
--- a/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/rename_class_member_test.dart
@@ -409,6 +409,33 @@ class A {
 ''');
   }
 
+  test_createChange_FieldElement_fieldFormalParameter_named() {
+    indexTestUnit('''
+class A {
+  final test;
+  A({this.test});
+}
+main() {
+  new A(test: 42);
+}
+''');
+    // configure refactoring
+    createRenameRefactoringAtString('test;');
+    expect(refactoring.refactoringName, 'Rename Field');
+    expect(refactoring.oldName, 'test');
+    refactoring.newName = 'newName';
+    // validate change
+    return assertSuccessfulRefactoring('''
+class A {
+  final newName;
+  A({this.newName});
+}
+main() {
+  new A(newName: 42);
+}
+''');
+  }
+
   test_createChange_FieldElement_invocation() {
     indexTestUnit('''
 typedef F(a);