Fix lints: unnecessary_brace_in_string_interp

pkg/analysis_server/lib/src/services/refactoring/rename_constructor.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 services.src.refactoring.rename_constructor;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/source_range.dart';
@@ skipping 41 matching lines @@
 
   @override
   Future fillChange() async {
     if (!element.isSynthetic) {
       // prepare references
       List<SearchMatch> matches = await searchEngine.searchReferences(element);
       List<SourceReference> references = getSourceReferences(matches);
       // append declaration
       references.add(_createDeclarationReference());
       // update references
-      String replacement = newName.isEmpty ? '' : '.${newName}';
+      String replacement = newName.isEmpty ? '' : '.$newName';
       for (SourceReference reference in references) {
         reference.addEdit(change, replacement);
       }
     }
   }
 
   void _analyzePossibleConflicts(RefactoringStatus result) {
     // check if there are members with "newName" in the same ClassElement
     ClassElement parentClass = element.enclosingElement;
     for (Element newNameMember in getChildren(parentClass, newName)) {
@@ skipping 10 matching lines @@
     SourceRange sourceRange;
     if (element.periodOffset != null) {
       sourceRange = rangeStartEnd(element.periodOffset, element.nameEnd);
     } else {
       sourceRange = rangeStartLength(element.nameEnd, 0);
     }
     String file = element.source.fullName;
     return new SourceReference(file, sourceRange, element, true, true);
   }
 }