Make analyzer strong-mode clean

pkg/analyzer/lib/src/generated/engine.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 analyzer.src.generated.engine;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1216 matching lines @@
 
   /**
    * A flag indicating whether mixins are allowed to inherit from types other
    * than Object, and are allowed to reference `super`.
    */
   bool enableSuperMixins = false;
 
   @override
   bool enableTiming = false;
 
-  @override
-  bool enableTrailingCommas = true;
-
   /**
    * A flag indicating whether errors, warnings and hints should be generated
    * for sources that are implicitly being analyzed.
    */
   bool generateImplicitErrors = true;
 
   /**
    * A flag indicating whether errors, warnings and hints should be generated
    * for sources in the SDK.
    */
@@ skipping 1456 matching lines @@
    * The data that was created from the source.
    */
   final E data;
 
   /**
    * Initialize a newly created holder to associate the given [data] with the
    * given [modificationTime].
    */
   TimestampedData(this.modificationTime, this.data);
 }