Fix lints: unnecessary_brace_in_string_interp

pkg/analysis_server/lib/src/computer/computer_outline.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 computer.outline;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/collections.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart' as engine;
@@ skipping 181 matching lines @@
   Outline _newConstructorOutline(ConstructorDeclaration constructor) {
     Identifier returnType = constructor.returnType;
     String name = returnType.name;
     int offset = returnType.offset;
     int length = returnType.length;
     SimpleIdentifier constructorNameNode = constructor.name;
     bool isPrivate = false;
     if (constructorNameNode != null) {
       String constructorName = constructorNameNode.name;
       isPrivate = Identifier.isPrivateName(constructorName);
-      name += '.${constructorName}';
+      name += '.$constructorName';
       offset = constructorNameNode.offset;
       length = constructorNameNode.length;
     }
     _SourceRegion sourceRegion = _getSourceRegion(constructor);
     FormalParameterList parameters = constructor.parameters;
     String parametersStr = parameters != null ? parameters.toSource() : '';
     Element element = new Element(
         ElementKind.CONSTRUCTOR,
         name,
         Element.makeFlags(
@@ skipping 186 matching lines @@
 }
 
 /**
  * A range of characters.
  */
 class _SourceRegion {
   final int length;
   final int offset;
   _SourceRegion(this.offset, this.length);
 }