fix hints from analyzer in analyzer

pkg/analyzer/lib/src/generated/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/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 317 matching lines @@
     }
     return _elementReference;
   }
 
   @override
   AnalysisContext get context => _resynthesizer.context;
 
   @override
   String get displayName => actualElement.displayName;
 
+  @deprecated
   @override
   SourceRange get docRange => actualElement.docRange;
 
   @override
   String get documentationComment => actualElement.documentationComment;
 
   @override
   Element get enclosingElement => actualElement.enclosingElement;
 
   @override
@@ skipping 741 matching lines @@
 }
 
 /**
  * TODO(scheglov) invalid implementation
  */
 class WeakReference<T> {
   final T value;
   WeakReference(this.value);
   T get() => value;
 }