Change MirrorSystem.libraries to Map<Uri, String>

tests/compiler/dart2js/bad_loop_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.
 
 import 'package:expect/expect.dart';
 import 'memory_source_file_helper.dart';
 
 import '../../../sdk/lib/_internal/compiler/compiler.dart'
        show Diagnostic;
 
 main() {
-  Uri cwd = getCurrentDirectory();
-  Uri script = cwd.resolve(nativeToUriPath(new Options().script));
+  Uri script = currentDirectory.resolve(nativeToUriPath(new Options().script));
   Uri libraryRoot = script.resolve('../../../sdk/');
   Uri packageRoot = script.resolve('./packages/');
 
   MemorySourceFileProvider.MEMORY_SOURCE_FILES = MEMORY_SOURCE_FILES;
   var provider = new MemorySourceFileProvider();
   int warningCount = 0;
   int errorCount = 0;
   void diagnosticHandler(Uri uri, int begin, int end,
                          String message, Diagnostic kind) {
     if (kind == Diagnostic.VERBOSE_INFO) {
@@ skipping 33 matching lines @@
   }
 
   for ((){}() in []) {
   }
 
   for (1 in []) {
   }
 }
 """
 };