Fix some analysis issues.

pkg/dev_compiler/test/worker/worker_test.dart

 // Copyright (c) 2016, 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 'dart:convert';
 import 'dart:io';
 
 import 'package:bazel_worker/bazel_worker.dart';
 // TODO(jakemac): Remove once this is a part of the testing library.
 import 'package:bazel_worker/src/async_message_grouper.dart';
 import 'package:bazel_worker/testing.dart';
-import 'package:path/path.dart' show join, joinAll, toUri;
+import 'package:path/path.dart' show join, joinAll;
 import 'package:test/test.dart';
 
 File file(String path) => new File(joinAll(path.split('/'))).absolute;
 
 main() {
   var dartdevc = join('bin', 'dartdevc.dart');
   group('Hello World', () {
     final argsFile = file('test/worker/hello_world.args');
     final inputDartFile = file('test/worker/hello_world.dart');
     final outputJsFile = file('test/worker/out/hello_world.js');
@@ skipping 343 matching lines @@
 Future<WorkResponse> _readResponse(MessageGrouper messageGrouper) async {
   var buffer = (await messageGrouper.next) as List<int>;
   try {
     return new WorkResponse.fromBuffer(buffer);
   } catch (_) {
     var bufferAsString =
         buffer == null ? '' : 'String: ${UTF8.decode(buffer)}\n';
     throw 'Failed to parse response:\nbytes: $buffer\n$bufferAsString';
   }
 }