Read SDK and patches from a JSON file.

pkg/front_end/lib/src/base/processed_options.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 
 import 'package:front_end/compiler_options.dart';
 import 'package:front_end/file_system.dart';
 import 'package:front_end/src/fasta/translate_uri.dart';
 import 'package:front_end/src/base/performace_logger.dart';
@@ skipping 117 matching lines @@
 
   /// Get the [TranslateUri] which resolves "package:" and "dart:" URIs.
   ///
   /// This is an asynchronous method since file system operations may be
   /// required to locate/read the packages file as well as SDK metadata.
   Future<TranslateUri> getUriTranslator() async {
     if (_uriTranslator == null) {
       await _getPackages();
       // TODO(scheglov) Load SDK libraries from whatever format we decide.
       // TODO(scheglov) Remove the field "_raw.dartLibraries".
-      _uriTranslator = new TranslateUri(_packages, _raw.dartLibraries);
+      _uriTranslator = new TranslateUri(
+          _packages, _raw.dartLibraries, const <String, List<Uri>>{});
       _uriTranslator.dartLibraries.addAll(_raw.dartLibraries);
     }
     return _uriTranslator;
   }
 
   /// Get the package map which maps package names to URIs.
   ///
   /// This is an asynchronous getter since file system operations may be
   /// required to locate/read the packages file.
   Future<Map<String, Uri>> _getPackages() async {
@@ skipping 24 matching lines @@
       // automagically.
       throw new UnimplementedError();
     }
     var root = _raw.sdkRoot;
     if (!root.path.endsWith('/')) {
       root = root.replace(path: _sdkRoot.path + '/');
     }
     return root;
   }
 }