remove warning that is no longer in dart:html

tests/compiler/dart2js/analyze_api_test.dart

 // Copyright (c) 2013, 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 analyze_api;
 
 import "package:expect/expect.dart";
 import '../../../sdk/lib/_internal/libraries.dart';
 import 'analyze_helper.dart';
 
 /**
  * Map of white-listed warnings and errors.
  *
  * Only add a white-listing together with a bug report to dartbug.com and add
  * the bug issue number as a comment on the white-listing.
  *
  * Use an identifiable suffix of the file uri as key. Use a fixed substring of
  * the error/warning message in the list of white-listings for each file.
  */
 // TODO(johnniwinther): Support canonical URIs as keys and message kinds as
 // values.
 const Map<String, List<String>> WHITE_LIST = const {
-  'path_observer.dart':
-      const ['Hint: Using "new Symbol"', // Issue 10565.
-            ],
   'sdk/lib/html/dart2js/html_dart2js.dart':
       const ['Hint: The class "Rect" overrides "operator==", '
              'but not "get hashCode".',
              'Hint: The class "Point" overrides "operator==", '
              'but not "get hashCode".',
              'Hint: The class "_ClientRect" overrides "operator==", '
              'but not "get hashCode".',
       ],
 };
 
 void main() {
   var uriList = new List<Uri>();
   LIBRARIES.forEach((String name, LibraryInfo info) {
     if (info.documented) {
       uriList.add(new Uri(scheme: 'dart', path: name));
     }
   });
   analyze(uriList, WHITE_LIST);
 }