Fix analyzer hints and warnings in test/.

test/run/resource_test.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.
 
-import 'dart:async';
-
-import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 const TRANSFORMER = """
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 
@@ skipping 147 matching lines @@
 
     var pub = pubRun(args: ["foo:script"]);
 
     // TODO(nweiz): Enable this when sdk#23990 is fixed.
     // pub.stdout.expect(p.toUri(p.join(sandboxDir, "foo/lib/resource.txt")));
 
     pub.stdout.expect("hello!");
     pub.shouldExit(0);
   });
 }