Analyzer support for `@factory` methods (linter#253).

pkg/analyzer/lib/src/dart/element/handle.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.element_handle;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 339 matching lines @@
   @override
   Element get enclosingElement => actualElement.enclosingElement;
 
   @override
   int get hashCode => _location.hashCode;
 
   @override
   bool get isDeprecated => actualElement.isDeprecated;
 
   @override
+  bool get isFactory => actualElement.isFactory;
+
+  @override
   bool get isJS => actualElement.isJS;
 
   @override
   bool get isOverride => actualElement.isOverride;
 
   @override
   bool get isPrivate => actualElement.isPrivate;
 
   @override
   bool get isProtected => actualElement.isProtected;
@@ skipping 743 matching lines @@
 
   @override
   bool get isStatic => actualElement.isStatic;
 
   @override
   DartType get type => actualElement.type;
 
   @override
   DartObject computeConstantValue() => actualElement.computeConstantValue();
 }