dart2js cleanup: remove unused imports and variables

pkg/compiler/samples/jsonify/jsonify.dart

Index: pkg/compiler/samples/jsonify/jsonify.dart
diff --git a/pkg/compiler/samples/jsonify/jsonify.dart b/pkg/compiler/samples/jsonify/jsonify.dart
index db8020d328f72fc695de7d93237d6085442cc7dc..a84cb043ea79570b6ddbc0c341769e66a8ef3629 100644
--- a/pkg/compiler/samples/jsonify/jsonify.dart
+++ b/pkg/compiler/samples/jsonify/jsonify.dart
@@ -3,18 +3,15 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:io';
 import 'dart:convert';
-
+import 'dart:io';
 import 'dart:mirrors';
 
-import 'package:sdk_library_metadata/libraries.dart'
-    show libraries, LibraryInfo;
+import 'package:sdk_library_metadata/libraries.dart' show libraries;
 
+import '../../lib/src/filenames.dart';
 import '../../lib/src/mirrors/analyze.dart' show analyze;
 import '../../lib/src/mirrors/dart2js_mirrors.dart' show BackDoor;
-
-import '../../lib/src/filenames.dart';
 import '../../lib/src/source_file_provider.dart';
 import '../../lib/src/util/uri_extras.dart';