Update to support analyzer version 0.28.0.

lib/src/dart_sdk.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 code_transformers.src.dart_sdk;
 
 import 'dart:io' show Directory;
 
 /// Note that the Analyzer has two versions of SdkAnalysisContext (and lots of
 /// other classes) with different signatures: can't mix the two.
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisOptions, InternalAnalysisContext, TimestampedData;
 import 'package:analyzer/src/context/context.dart' show SdkAnalysisContext;
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/sdk_io.dart' show DirectoryBasedDartSdk;
 import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/summary/idl.dart';
 import 'package:cli_util/cli_util.dart' as cli_util;
 
 /// Attempts to provide the current Dart SDK directory.
 ///
 /// This will return null if the SDK cannot be found
 ///
 /// Note that this may not be correct when executing outside of `pub`.
 String get dartSdkDirectory {
   Directory sdkDir = cli_util.getSdkDir();
   return sdkDir != null ? sdkDir.path : null;
@@ skipping 138 matching lines @@
       _sources[uri] =
           src = new _MockSdkSource(uri, 'library dart.${uri.path};');
     }
     return src;
   }
 
   @override
   Source fromFileUri(Uri uri) {
     throw new UnsupportedError('MockDartSdk.fromFileUri');
   }
+
+  @override
+  PackageBundle getLinkedBundle() => null;
 }
 
 class _MockSdkSource implements UriAnnotatedSource {
   /// Absolute URI which this source can be imported from.
   final Uri uri;
   final String _contents;
 
   Source get source => this;
 
   Source get librarySource => null;
@@ skipping 74 matching lines @@
   'dart:async': '''
         class Future<T> {
           Future then(callback) {}
         class Stream<T> {}
   ''',
   'dart:html': '''
         library dart.html;
         class HtmlElement {}
         ''',
 };