Fix for subscribing for notifications for files in packages.

pkg/analysis_server/test/mock_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 testing.mock_sdk;
 
 import 'package:analyzer/file_system/file_system.dart' as resource;
 import 'package:analyzer/file_system/memory_file_system.dart' as resource;
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
@@ skipping 205 matching lines @@
   @override
   Source fromFileUri(Uri uri) {
     String filePath = uri.path;
     String libPath = '/lib';
     if (!filePath.startsWith("$libPath/")) {
       return null;
     }
     for (SdkLibrary library in LIBRARIES) {
       String libraryPath = library.path;
       if (filePath.replaceAll('\\', '/') == libraryPath) {
-        String path = library.shortName;
         try {
           resource.File file = provider.getResource(uri.path);
-          Uri dartUri = new Uri(scheme: 'dart', path: path);
+          Uri dartUri = Uri.parse(library.shortName);
           return file.createSource(dartUri);
         } catch (exception) {
           return null;
         }
       }
       if (filePath.startsWith("$libraryPath/")) {
         String pathInLibrary = filePath.substring(libraryPath.length + 1);
         String path = '${library.shortName}/${pathInLibrary}';
         try {
           resource.File file = provider.getResource(uri.path);
@@ skipping 62 matching lines @@
   bool get isInternal => throw unimplemented;
 
   @override
   bool get isShared => throw unimplemented;
 
   @override
   bool get isVmLibrary => throw unimplemented;
 
   UnimplementedError get unimplemented => new UnimplementedError();
 }